AEI Site Optimization Procedure
Railnet AEI System Site Installation Manual
This chapter explains the APU application software and the procedures for optimizing all AEI system components.
APU Application Software
Local and Remote User Access
There are three types of user access available; local, remote, and network. Local access requires a computer equipped with a standard communications package and a null‐modem cable from the local port of the APU‐102 to the computer. Remote access requires a computer equipped with a Hayes compatible modem and a standard communications package. Telnet connection requires the APU‐102 has network capable hardware and software as well as a valid network path to the APU, via WAN remotely or LAN at the site.
The default communications settings are:
Type |
Baud Rate |
Word Length |
Parity |
Stop Bits |
|---|---|---|---|---|
Local |
2400 |
8 | N | 1 |
Remote |
Modems will negotiate best speed |
8 | N | 1 |
Network |
Handled by TCP/IP protocol |
|
|
|
Table 3.1: Communications Settings
APU-102 Software Programs
The APU‐102 uses two different software programs. The first is the AEI application software, which runs the APU‐102’s normal functions. Comet Electronics incorporates its standard remote support into this application software. The second is a standalone “fail‐safe” software program, used mainly for recovery and diagnostics. There are various versions of the fail‐safe program depending on configuration of the APU‐102. Mini Remote Support (MRS, Start‐up ROM version 4.1) or ROMSHELL (Start‐up ROM version 5.0+). When the SYS light (LED) is on steadily, the APU‐102 is running the APU application software. When the SYS light (LED) is flashing, the APU‐102 is running MRS/ROMSHELL. With addition of network connections to the APU‐102, NetMRS, a network capable version of ROMSHELL was created. It has all the functions/commands of ROMSHELL, but local, remote, and network connectivity are made using the AEI Application’s parameter set.
-
AEI Application Software
The AEI application software is the heart of the APU‐102. It is stored on the solid state disk along with the train information. It logs the train axles, correlates the axles into cars, and puts the tags with the cars. It is a multitasking program that allows the system to record a train output to both a remote unit and a local unit at the same time.
When the AEI application software is running, you connect to the APU‐102 via the Front Door. Connecting via the Front Door allows you to define the system parameters and individual session parameters, delete trains, and view the systems log, for example. The Front Door is generally used unless there is a problem with the AEI application software.
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Mini Remote Support (MRS) Start-up ROM 4.1 and earlier
Mini Remote Support (MRS, Start‐up ROM version 4.1) is a version of the Comet Electronics Remote Support software. When this program or the APU application software is running (version 4.x only), you can log into the APU site’s Back Door. Logging into the Back Door via the MRS program allows you to dial in to the APU, transfer individual files, and download new code. However, these functions are not menu‐driven. A special communication program, “Remote Support,” is required to connect to an APU‐102 to use MRS’s features. “Remote Support” is only compatible PCs running MS‐DOS and using legacy hardware ports and modems.
The Comet Electronics MRS is programmed or burned into an EPROM at the Comet Electronics facility before the unit is shipped to the customer. The use of the EPROM makes the software uneraseable. The APU‐102 boots to the EPROM first, then looks to see if the APU application software is available. If there is any problem with the APU application software, the APU‐102 loads the MRS program.
Every fifth time the APU hard boots (power reset or watchdog timer reboot), the MRS program is loaded, stays in MRS mode for 20 minutes, then reboots. To force the APU‐102 into MRS mode, press and hold the SYS button, then turn on the APU‐ 102. Hold the SYS button until the SYS LED flashes slowly (about once per second).The EPROM is located on the USSD card and can be identified by the name ʺStart‐ up ROMʺ, version and USSD capacity.
Note: The reboot command (soft boot) from the Front Door (standard AEI application interface) does not increment this counter.
ROMSHELL Start-up ROM version 5.0 or higher
ROMSHELL (Start‐up ROM version 5.0+) replaces MRS. It has expanded functionality compared to MRS listed above, but is accessible with any commercial communication software program. The ROMSHELL interface is detailed in the AEI System Operations Manual.
The EPROM is located on the USSD or PCM‐SSD card and can be identified by the name ʺStart‐up ROMʺ, version and USSD capacity.
NetMRS
NetMRS is a network capable version of ROMSHELL. It is not loaded from the Startup ROM, but is an application running from the XPe kernel on the system’s Compact Flash memory. It has some additional capabilities compared to ROMSHELL, including network connectivity. The NetMRS interface is detailed in the AEI System Operations Manual.
Main Menu Options
There are two APU‐102 Main Menu options, the System Menu and the Supervisory Menu.
The System Menu functions provide accessibility to a wide range of reports and other information that can be generated from the stored data.
The Supervisory Menu provides functions to reconfigure the operational parameters of the APU‐102 as well as clearing the APU‐102 of all trains and status information. The same data is available whether accessing the APU‐102 from a remote site via the modem or on‐site via the local communications port. For detailed information about these menus, see the System Menu and Supervisory Menu sections later in this chapter.
Multiple Sessions
The APU‐102 supports up to ten virtual APUʹs. Each virtual APU, called a ʺsession,ʺ can be configured individually according to the needs of the railroad it supports.
Current versions of the AEI application include a new feature, NetMenu. It allows multiple devices to be accessed via one external connection. You may be presented with a menu BEFORE actually connecting to an APU. NetMenu is detailed later in this text. When accessing the site, the first question the APU‐102 software asks is which APU session you want to access. Each session has its own password protection, just like each physical APU would. (See Passwords.) Once you gain access to a session, any parameters you change affect only that session.
- Each session on the APU‐102 is capable of reporting consist and maintenance reports to the host of your choice. Sessions can be configured for different purposes. For example, a customer may set up Session 1 for standard consist and maintenance reporting to its normal host system, then configure Session 2 to report different types of information (such as scale reports) to other facilities on the railroad. This often happens when the host system to which the AEI reports are sent cannot handle the type of data the other facility needs.
- Each session uses the same tag information but is completely independent when formatting and transmitting the information. The owner of the APU‐102 is responsible for the initial setup of each session, while the session owner has the ability to customize the individual session. After you select a session, password entry is required.
Passwords
Comet Electronics delivers the systems with default passwords set up in the APU‐ 102. Both the System Menu and the Supervisory Menu are password protected. Also, a password is available for each session’s host interface. The System and Supervisory passwords are only visible under the Supervisory Menu display of the site parameters where separate password fields are maintained. Each session is independent of one another, so passwords for one session would not be available to other session users. The System Menu and the Supervisory Menu require different passwords from the host system. The following are the APU‐102 default passwords:
Default Passwords | |
|---|---|
System Menu |
Supervisory Menu |
SECRET |
SUPER |
Table 3.2: Default Passwords
Inactivity Time-outs
There are numerous inactivity timeouts built into the APU‐102. Their purpose is to remind the user that action has not been taken for a particular amount of time or to log the user off in case the user has forgotten to do so. At the Session Select menu, the APU‐102 pauses for three minutes. The APU‐102 then beeps and redisplays the Session Select menu. This represents one timeout period. The following table demonstrates how time‐outs work:
Screen |
Number of 3-minute inactivity time-outs allowed |
Result |
|---|---|---|
Session Select Menu |
3 | APU-102 logs user off. |
Password |
2 | Returns to Session Select menu screen. |
System Menu |
1 | APU-102 logs user off and returns to Session Select menu screen. |
Supervisory Menu |
1 | Returns to System Menu screen. |
Table 3.3: Inactivity Time-outs
On-line Help
3 APU-102 logs user off.
2 Returns to Session Select menu screen.
1 APU-102 logs user off and returns to Session Select menu screen.
1 Returns to System Menu screen. Table 3.3: Inactivity Time-outs
- Throughout the user command interface in the System Menu or Supervisory Menu, you may type a command followed by <?> to display available information about the command. If you do not remember the command, enter <?> at the command prompt and the software shows what commands you can currently use. Example: Typing <D><?> describes the Directory command and any options available with that command.
When entering commands in a string, always type a comma between them.
Example: To use the Check Tag Sequence (CT) command to verify that Reader0 and all antennas for a particular site are working correctly, enter CT,0,* for the command string. (Check Tag hardware required.)
System Optimization
- Power on the APU-102 to make sure the Search LEDs are operational. They should come on when power is applied and turn off once the APU-102 has initialized completely (approximately 45 seconds).
Local Connection
Laptop Computer Connections
1) Connect DB9F-DB25M RS232 null modem cable (or modem cable with null modem adapter) to serial port 1 or 2 of laptop computer and the local port of APU-102 located on the bottom of the APU-102.
2) Turn on laptop computer with any communications software that supports ANSI terminal emulation installed on computer.
3) Set communications parameters to 2400 baud, no parity, 1 stop bits, 8 data bits, no flow control. You are now ready to enter the Front Door of the APU-102.
Note: The local port on the APU may be configured differently depending on the customer’s operating standards. Set the communication program on your computer to match.
4) Select terminal emulation mode and press <Enter>. The APU application software prompts you to log in.
Log On To the APU-102
1) After connecting to the APU-102 through either the local or remote port (modem), press
<Enter> to activate the Session Select menu screen.
<span id="HTMLENTITY:1730179202678" style="font-family: courier new", courier;" class="mwt-preserveHtml">1. Comet Documentation <span id="HTMLENTITY:1730189841786" style="font-family: courier new", courier;" class="mwt-preserveHtml" >3. Inactive Session, Not Available for Selection <span id="HTMLENTITY:1730107958749" style="font-family: courier new", courier;" class="mwt-preserveHtml" >4. Inactive Session, Not Available for Selection <span id="HTMLENTITY:1730205913633" style="font-family: courier new", courier;" class="mwt-preserveHtml" >5. Log Off<span id="HTMLENTITY:1730173099692" style="font-family: courier new", courier;" class="mwt-preserveHtml" >Select the Appropriate Session # ( 1, 2, 3, 4 or 5 ) Session #: _ |
Options 1 ‐ 4 on this menu represent the four available sessions in the APU‐102. Option 5 logs you off the Session Select menu and, if accessed through the remote port, disconnects the modem. Additional sessions only appear if configured. If more than 4 sessions are active, “X” will logoff.
2) To log on to a session, enter the number corresponding to the desired session. The APU-102 will request the password for the session. 3) Enter the correct system password. The system and supervisory password fields are a maximum of six ASCII, printable characters. :NOTE: Versions after 5.0 have a password limit of seven characters. As the password is entered, an asterisk (*) displays where you type the character. After the correct system password is entered and accepted, the Logon menu displays and the cursor flashes at the APU102XP: Main prompt with the current session number.<span id="HTMLENTITY:1730160480999" style="font-family: courier new", courier;" class="mwt-preserveHtml">Comet Documentation <span id="HTMLENTITY:1730132339357" style="font-family: courier new", courier;" class="mwt-preserveHtml">USID: Comet0ICU812 Site Name: Test APU102XP:Main 1>_ |
Initial Configuration and Tests
1) Check the current software version and update if needed. To verify that the APU-102 has the correct software version running, log into the Main prompt, press the "/" key, then <Enter>. This shows the current running version. Check with Comet Electronics Customer Service to see if an update is needed.
2) Before a train can be recorded properly, acquisition parameters need to be set to site- specific values (transducer spacing, gain and threshold, antenna read lobes and reader configuration, inter-track communications, and REDI interface - if site is a hybrid).
3) Update the site Operating parameters. Because each site may vary, the operating parameters need to be checked to make sure they apply to the site you are working on. Change to the Supervisory Menu to perform editing functions. A reboot is required to activate parameter changes.
4) Update the site Session parameters. If there is a phone line available for transmission to the host, update Session parameters as required and test the Host Reporting operation.
5) Verify the AC power fail transformer operation by observing the I/O screen while testing. Log onto the APU-102 and Press the “I” key, then <Enter> at the APU102XP: Main prompt. Observe the 24 VAC line. I/O information is continuously updated.
NOTE: Communications software must be in ANSI mode to read this screen.
6) Verify AC power fail test. To do this, turn off breaker to AC power fail transformer, wait 10 seconds and turn back on. Log on to APU-102 and change to the Supervisory Menu. Enter the SYS command, PID 1, and verify you see the following messages in the system error log. Verify the power fail messages occur at the same time that the breaker was tripped and reset.
AC Pwr Fail |
Followed by:
AC Pwr Restored |
RF Power Optimization
Equipment Required
The following equipment is necessary to optimize RF power:
Bird RF Power Analyst Model 4381 with 5W (400-1000 MHz) and 500mW-(850-960 MHz) elements or equivalent
N to N Coax cable 4 ft (Male both ends)
50 ohm 5W terminator
Programmed passive transponder tag mounted to metal backplate, at least 3 times the size of the tag.
Digital multi-meter
Watt Meter Setup
1) Install 5W 400-1000 MHz element into the forward element receptacle.
2) Install 500mW 850-960 MHz element into the reflected element receptacle.
3) Range 5, X1 scale.
Railcar-Only Site (Single Reader - Multiplexed RF)
1) Make sure RF power is off. The Search 0 and 1 LEDs on the APU-102 front panel should be off when RF is off to both channels.2) Enter the RFON command from either menu and turn both channels of Reader 0 on by typing the RFON,0,* command. This turns RF on for both Channel 0 and Channel 1 of Reader 0.
3) With a digital multi-meter on the DC V scale, measure the RF PWR at the RF unit. Place your positive lead on the AR2200 RF unit RF PWR terminal and the negative lead on the RF GND terminal inside the AR2200 RF unit.
4) Setting RF unit source voltage
a) AR2200, Version 1
With both RF channels on in multiplex mode, the RF PWR should be no less than 12.5 VDC and no more than 13 VDC. The RF PWR is supplied from the adjustable 12v power supply inside the APU-102. Adjust VR1 on the APU-102 power supply board for Reader 1 until the RF PWR at the RF unit is at least 12.9 VDC. If this is not done, all power measurements from this point forward may be incorrect.
b) AR2200, Version 2
The version 2 AR2200 has a two-color power indicator LED. Adjust VR1 on the APU-102 power supply board for Reader 1 so the power indicator LED is green with the RF in either active or idle modes.
NOTE |
DC voltage is regulated on Version 2 RF modules and changing the supply voltage will have no effect on the RF power output. If the AR2200 installed at the site is Version 2, disregard any references to adjust the voltage later in this text. |
Caution |
Verify RF power is off before connecting or disconnecting any RF cables in the sections that follow. Press any key to turn off RF power. Make sure Search 0 and 1 on front panel of APU- 102 are off. |
RF Power at Source
1) Measure power at the starting point, or source, first. If it is low here, the rest of the system will not operate correctly.
2) Make sure RF power is off to RF unit.
3) Find the N-N jumper running from the RF unit Channel 0 to the coax lightning arrestor. Disconnect from arrestor end and connect to Forward element of RF meter.
4) Connect 50 ohm 5W terminator to the reflected element of the watt meter.
5) Enter the RFON command from either menu. To turn on RF to Channel 0 only, type the
RFON,0,0 command.
6) Turn on watt meter and press the FWD PEP button. This displays the forward peak envelope power. The power at the RF source should be no less than 1.4W. The forward power at source should not exceed 2W.
7) If the forward power is less than 1.40W with the 4-foot jumper in, you can try adjusting the 12v supply voltage up to gain some RF PWR. Make sure you do not exceed 13VDC RF PWR. If adjusting the RF PWR up does not bring the forward power up to at least 1.4W, the AR2200 must be replaced or repaired. The same is true for power over 2W.
If you cannot adjust RF PWR down enough to get the forward power under 2W, replace the AR2200. Do not attempt to adjust the RF unit’s supply voltage lower than 12.5 VDC.
8) Record measurements for future diagnostic evaluation.
9) Repeat above steps for Channel 1. Use the RFON,0,1 command to turn power on to Channel 1.
10) Press any key to turn off RF power. Make sure Search 0 and 1 on front panel of APU- 102 are off.
| Tip | The 5W element has a +/- 250mW tolerance rating. If you are unsure the readings are correct or suspect an RF unit out of specification, install the 500mW element in the forward element with (2) 3dB in-line attenuators to reduce the power below 500mW from the RF unit. Turn power on to the channel in question, note the reading, and divide the reading in half. This will give you a more accurate reading because the 500mW element has on a +/- 25mW tolerance and you will know within 25mW the actual power of the source. |
Standing Wave Ratio at Source
1) Remove 50 ohm terminator and attach coax coming from the antenna to the reflected element of the meter.
2) Turn RF power on to Channel 0 by typing the RFON,0,0 command from either menu.
3) Two elements are required for this mode and they must have a 10 to 1 power range ratio. Press the SWR key momentarily. If average reflected power is between 10% and 120% of full scale and the average reflected power is less than 120% of the reflected element range, SWR will be displayed. If any of the above conditions are not met, an error message will display. Two arrows pointing to the right (“greater than” symbols) indicate over-range, while two left pointing arrows (“less-than” symbols) indicate under- range or too little power.
4) The SWR should fall between 1.01 (0% reflected power) and 1.5 (4% reflected power). If the SWR exceeds 1.5 there could possibly be a bad connection or a coax cable problem. Double check the connectors for correct assembly. Too much reflected power degrades power at the antenna and causes low handshake counts on the transponder tags being read. Record results for future diagnostic use.
5) Repeat the above steps for Channel 1. Type the RFON,0,1 command for Channel 1. Record the results for future diagnostic use.
6) Press any key to turn RF power off.
7) Reconnect coax cables to original positions.
RF Power at Antenna
1) Disconnect coax cable from Antenna 0.
2) Connect coax to the forward element of the watt meter with the 50 ohm terminator still attached to the reflected element of the meter.
- 3) Turn on RF power to Channel 0 by typing the RFON,0,0 command from the either menu of the APU-102.
- 4) Press the FWD PEP key to measure peak envelope power. There should be no less than 1.0 watts of power at the antenna.
Standing Wave Ratio at Antenna
1) Remove 50 ohm terminator and attach N-N jumper from the antenna to the reflected element of the meter.
2) Turn RF power on to Channel 0 by typing the RFON,0,0 command from either menu.
3) Two elements are required for this mode and they must have a 10 to 1 power range ratio. Press the RFL PEP to measure the reflected peak envelope power. Record the results for future diagnostic use.
4) Press the SWR key momentarily. If average reflected power is between 10% and 120% of full scale and the average reflected power is less than 120% of the reflected element range, SWR will be displayed. If any of the above conditions are not met, an error message will display. Two arrows pointing to the right (“greater than” symbols) indicate over-range, while two left pointing arrows (“less-than” symbols) indicate under-range or too little power.
5) The SWR should fall between 1.01 (0% reflected power) and 1.5 (4% reflected power). If the SWR exceeds 1.5 there could possibly be a bad connection or a coax cable problem. Double check the connectors for correct assembly. Too much reflected power degrades power at the antenna and causes low handshake counts on the transponder tags being read. Record results for future diagnostic use.
6) Repeat the above steps for Channel 1. Type the RFON,0,1 command for Channel 1. Record the results for future diagnostic use.
7) Press any key to turn RF power off.
8) Reconnect coax cables to original positions.If Less Than 1W of Power at Antenna
1) Double check coax cable type to make sure correct cable is being used.
2) Double check RF PWR at RF unit to make sure you have at least 12.5VDC. You can increase this power to give you more power at the antenna as long as you do not exceed 2W at source and 13VDC of RF PWR. The reason for having at least 1W of power at the antenna is due to the speed of the site. If the site is high speed (above 45mph) the transponder tag will be in the read window a shorter amount of time therefore you will want the biggest read window possible to make sure the tag is read.
3) Double check SWR to make sure there is not excessive reflected power. 4) Record measurements for future diagnostic use.
- 5) Turn RF power off and reconnect coax to antenna.
- 6) Repeat these steps for Antenna 1.
Measuring Horizontal Read Window
1) The horizontal read window is defined as the horizontal distance a tag may be read in front of an antenna. The tag should be passed in front of antenna directly above edge of ties (approximately 4 ft). Tag should be held horizontally to insure accuracy of read window
2) Turn RF power on to Channel 0 only using the RFON,0,0 command from the either menu on the APU-102.
3) Make sure the Sonalert switch, which is located on the motherboard at the bottom of the APU-102, is in the correct reader position for the reader being measured. It should be set for Reader 1 or Reader 2. Refer to APU-102 system interconnect diagram in the AEI System Operations Manual for proper position of the switch.
4) Attach programmed passive transportation tag to metal plate approximately 3 times the size of the tag.
5) Listen for the Sonalert in the building and face Antenna 0 at the edge of the ties, approximately 10 feet to one side of the antenna. Simulate a tagged railcar passing the site by holding the tag attached to the 3’ x 2’ metal plate at the edge of the ties 3.5 feet from the top of the rail and walking on either side of the antenna until the Sonalert sounds.
6) Mark at the edge of ties where the Sonalert first came on.
7) Continue walking past the antenna with tag in the same position until the Sonalert stops. Mark this point at the edge of ties.
8) Measure from the point where the Sonalert first sounded to the point where it stopped with a tape measure. This will be the horizontal read window for this antenna.
9) Round the measurement up to the nearest foot. Horizontal read windows with at least 1W of power at antenna should be approximately 13-16 feet wide on a Parapanel antenna and approximately 7 feet ± 2 feet for a low profile antenna.
10) Record this measurement on paper for reference and in the APU-102 acquisition parameters under Reader 1 “Ant0PassiveLobe.”
11) Repeat the above steps for Antenna 1.
12) Record the measurement for Antenna 1 on paper for reference and in the APU-102 acquisition parameters under Reader 1 “Ant1PassiveLobe.”
| Tip | If expected window widths are not obtained and power levels are correct, check RF unit range potentiometer setting. |
Railcar-Only Site (Dual Reader - Dedicated RF)
NOTE |
For dual reader dedicated RF sites that there should be a separate AR2200 RF unit for each antenna. RF unit for Antenna 0 should have a 50 ohm terminator plugged into Channel 1, and the RF unit for Antenna 1 should have a 50 ohm terminator plugged into Channel 0. |
1) Make sure RF power is off by checking the Search 0 and 1 LEDs on the APU-102 front panel for both reader 1 and 2. When RF is off to both channels, all search LEDs should be off.
2) From either menu, enter the RFON command and type RFON,0,* to turn both channels of Reader 0 on. This turns on RF to both Channels 0 and 1 of Reader 0.
3) With a digital multi-meter on the DC V scale, measure the RF PWR at the RF unit. On the AR2200 place your positive lead on the RF PWR terminal and the negative on the RF GND terminal inside the AR2200 RF unit.
4) Setting RF unit source voltage
- a) AR2200,Version1
- With both RF channels on in multiplex mode, the RF PWR should be no less than 12.5 VDC and no more than 13 VDC. The RF PWR is supplied from the adjustable 12v power supply inside the APU-102. Adjust VR1 on the APU-102 power supply board for Reader 1 until the RF PWR at the RF unit is at least 12.9 VDC. If this is not done, all power measurements from this point forward may be incorrect.
- b) AR2200,Version2
- The version 2 AR2200 has a three-color power indicator LED. Adjust VR1 on the APU-102 power supply board for Reader 1 so the power indicator LED is green with the RF in either active or idle modes.
- 5) Repeat the above steps for Reader 1 by typing RFON,1,* to turn on RF to both channels of Reader 1. Adjust VR2 on the APU-102 power supply to adjust RF PWR for Reader 1.
-
RF Power at Source
1) Power should be measured at the starting point, or source, first. If it is low here, the rest of the system will suffer.
- 2) Make sure RF PWR is off to RF unit. Find the N-N jumper running from the RF unit #1 Channel 0 to the coax lightning arrestor. Disconnect from arrestor end and connect to Forward element of RF meter.
- 3) Connect the 50 ohm 5W terminator to the reflected element of the watt meter
- 4) From either menu, select the RFON command. Turn on RF to Channel 0 only by typing RFON,0,0.
- 5) Turn on watt meter and press the FWDCW PEP button. This displays the forward peak envelope continuous wave power. The power at the RF source should be no less than 1.4 W. The forward power at source should not exceed 2W.
- 6) If the forward power is less than 1.40W with the 4-foot jumper in, you can try adjusting the 12v supply voltage up to gain some RF PWR. Make sure you do not exceed 13VDC RF PWR. If adjusting the RFPWR up does not bring the forward power up to at least 1.4W, the AR2200 must be replaced or repaired. The same is true for power over 2W. If you cannot adjust RF PWR down enough to get the forward power under 2W, replace the AR2200. Do not attempt to adjust the RF unit’s supply voltage lower than 12.5 VDC.
- 7) Record measurements for future diagnostic evaluation.
- 8) Repeat the above steps for Channel 1. Use the RFON,1,1 command to turn power on to Reader 1, Channel 1.
- 9) Press any key to turn RF power off. Make sure Search 0 and 1 for both readers on front panel of APU-102 are off.
Tip |
The 5W element has a +/- 250mW tolerance rating. If you are unsure if the readings are correct or suspect a RF unit out of specification, install the 500mW element in the forward element with (2) 3dB in-line attenuators to reduce the power below 500mW from the RF unit. Turn power on to the channel in question and note the reading. Divide the reading in half. This will give you a more accurate reading because the 500mW element has on a +/- 25mW tolerance and you will know within 25mW the actual power of the source. |
Standing Wave Ratio at Source
1) Remove the 50 ohm terminator and attach coax coming from antenna to the reflected element of the meter.
2) Turn RF power on to Reader 0, Channel 0 by typing RFON,0,0 from either menu.
3) Two elements are required for this mode and they must have a 10 to 1 power range ratio. Press the SWR key momentarily. If the average reflected power is between 10% and 120% of full scale and the average reflected power is less than 120% of the reflected element range, SWR will display. If any of the above conditions are not met, an error message will display. Two arrows pointing to the right (“greater than” symbols) indicate over-range, while two left pointing arrows (“less-than”) symbols indicate under- range or too little power.
- 4) The SWR should fall between 1.01 (0% reflected power) and 1.5 (4% reflected power). If the SWR exceeds 1.5, there could possibly be a bad connection or a coax cable problem. Double check the connectors for correct assembly. Too much reflected power degrades power at the antenna and causes low handshake counts on the Transponder tags being read. Record results for future diagnostic use.
- 5) Repeat the above steps for Reader 1, Channel 1. Type RFON,1,1 for Reader 1, Channel 1. Record results for future diagnostic use.
- 6) Press any key to turn RF power off.
- 7) Reconnect coax cables to original positions.
-
RF Power at Antenna
1) Disconnect coax cable from Antenna 0.
2) Connect coax to the forward element of the watt meter with the 50 ohm terminator still attached to the reflected element of the meter.
3) Turn on RF power to Reader 0, Channel 0 by typing (Reader 1 or Reader 2) from either menu of the APU-102.
4) Once again press the FWD PEPCW key to measure peak envelope continuous wave power. There should be no less than 1.0 watts of power at the antenna.
Standing Wave Ratio at Antenna
1) Remove 50 ohm terminator and attach N-N jumper from the antenna to the reflected element of the meter.
2) Turn RF power on to Reader 0, Channel 0 by typing the RFON,0,0 command from either menu.
3) Two elements are required for this mode and they must have a 10 to 1 power range ratio. Press the RFL PEP to measure the reflected peak envelope power. Record the results for future diagnostic use.
4) Press the SWR key momentarily. If average reflected power is between 10% and 120% of full scale and the average reflected power is less than 120% of the reflected element range, SWR will be displayed. If any of the above conditions are not met, an error message will display. Two arrows pointing to the right (“greater than” symbols) indicate over-range, while two left pointing arrows (“less-than” symbols) indicate under-range or too little power.
5) The SWR should fall between 1.01 (0% reflected power) and 1.5 (4% reflected power). If the SWR exceeds 1.5 there could possibly be a bad connection or a coax cable problem. Double check the connectors for correct assembly. Too much reflected power degrades power at the antenna and causes low handshake counts on the Transponder tags being read. Record results for future diagnostic use.
- 6) Repeat the above steps for Reader 1, Channel 1. Type the RFON,1,1 command for Reader 1, Channel 1. Record the results for future diagnostic use.
- 7) Press any key to turn RF power off.
- 8) Reconnect coax cables to original positions.
If Less Than 1W of Power at Antenna
1) Double check coax cable type to make sure correct cable is being used.
2) Double check RF PWR at RF unit to make sure you have at least 12.5VDC. You can increase this power to provide more power at the antenna as long as you do not exceed 2W at source and 13VDC of RF PWR. The reason for having at least 1W of power at the antenna is due to the speed of the site. If the site is high speed (above 45mph), the Transponder tag will be in the read window a shorter amount of time. You will, therefore, want the largest read window possible to make sure the tag is read.
3) Double check SWR to make sure there is not an excessive reflected power. 4) Record measurements for future diagnostic use.
5) Turn RF power off and reconnect coax to antenna.
6) Repeat above steps for Reader 1 Antenna 1 using the RFON,1,1 command.Measuring Horizontal Read Window
1) The horizontal read window is defined as the horizontal distance in front of an antenna that a tag may be read. The tag should be passed in front of antenna directly above edge of ties (approximately 4 ft). Hold the tag horizontally to ensure accuracy of read window.
2) Turn RF power on to Reader 0 Channel 0 only, using the RFON,0,0 command from either menu on the APU-102.
3) Make sure the Sonalert switch, which is located on the motherboard, is turned on for Reader 1. Refer to APU-102 system interconnect diagram in 3.0 AEI System Components and Functions in the AEI System Operations Manual for proper switch position.
4) Attach programmed passive transportation tag to metal plate approximately 3 times the size of the tag.
5) Listen for the Sonalert in the building. Face Antenna 0 at the edge of the ties, approximately 10 feet to one side of the antenna. Simulate a tagged rail car passing the site by holding the tag attached to the 3’ x 2’ metal plate at the edge of the ties 3.5 feet from the top of the rail and walking on either side of the antenna until the Sonalert sounds. Mark at the edge of ties where the Sonalert first came on and continue walking past the antenna with tag in same position until the Sonalert stops, mark this point at the edge of ties. Measure from the point where the Sonalert first sounded to the point where it stopped with a tape measure, this will be the horizontal read window for this antenna.
6) Round measurement up to the nearest foot.
7) Horizontal read windows with at least 1W of power at antenna should be approximately 13-16 feet wide on a Parapanel antenna and 7 feet +/- 2 feet for a low profile antenna.
8) Record this measurement on paper as a record and in the APU-102 Acquisition parameters for Reader 1 “Ant0PassiveLobe”.
9) Repeat above steps for Reader 1 Antenna 1 using the RFON,1,1 command. 10) Record measurement for Antenna 1 on paper and in the APU-102 Acquisition
parameters for Reader 2 “Ant1PassiveLobe”.
Tip |
If expected window widths are not obtained and power levels are correct, check RF unit range potentiometer setting. |
RF Module Range Sensitivity Adjustment
The range sensitivity adjustment feature of the AR2200 RF module provides a means for unwanted tag signals to be screened without decreasing RF power. This feature may be used to desensitize the reading range of the system.
The range sensitivity modulator allows selective setting of the effective noise threshold of the system. This is accomplished by injecting AM modulation onto the IF signals, thus increasing the threshold noise level. A tag signal is decoded as valid by the reader only when its signal exceeds the preset threshold.
NOTE |
This adjustment can impact tag read range and performance. Comet Electronics does not use this adjustment in an attempt to control read performance. Installing a jumper at JP1, near the transformer on the RF interface board, disables the range sensitivity adjustment. The range is pre-adjusted to maximum, but installing the jumper ensures the maximum range. |
Older RF units produced prior to 1993 may not have the jumper override option and must be manually adjusted. Adjustments are made to the range sensitivity potentiometer located on the RF interface board. If range potentiometers are the small plastic type, set the maximum range by turning the potentiometers fully counterclockwise (CCW). These multi‐turn potentiometers usually have click stops. For potentiometers without click stops, turn 4 full rotations counterclockwise. If range potentiometers are the large metal type, set the maximum range by turning the potentiometers fully clockwise (CW).
