Peninsula Engineering Solutions RMAS-120 User manual

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
Peninsula Engineering Solutions may change specifications as necessary to meet industry requirements. © 2014 Peninsula Engineering Solutions, inc.
Peninsula Engineering Solutions, inc. Telephone [phone]
POB 1095 Facsimile [phone]
Danville, California 94526, USA Internet www.peninsulaengineering.com
RMAS-120 Trouble Shooting Guide
Introduction
The RMAS-120 Repeater Monitor and Alarm System
provides supervision of microwave RF repeaters.
Alarm and status information is encoded into a serial
data stream that is then amplitude modulated on the
microwave carriers being amplified by the RF
repeater. In some cases, this serial data stream
(telemetry) is carried by an auxiliary UHF radio link.
The telemetry signal and RMAS-120 are designed to
be compatible with a wide range of microwave radio
terminal equipment.
With the wide range in equipment and circumstances
of the applications, there are times when the data
recovery may be difficult to setup. This trouble-
shooting guide is intended to assist in diagnosing and
resolving many common problems.
The telemetry data is sent at a very slow rate in order
to be compatible with most radio Automatic Gain
Control, AGC circuits. The data timing fits within the
frequency range of natural fast fading (100
dB/second or 1dB/10 msec).
Common Problems
1. Receiver does not synchronize
1.1. The most common reasons the receiver will
not synchronize are:
•No or Weak Signal
•Interference
•Inverted Data
•Incompatible AGC
2. Basic Checks
2.1. Check RMAS-120 Transmitter for the
following:
2.1.1. DC Power is applied and main switch is ON.
2.1.2. Modulation switches are set for the intended
direction of transmission. Note: 2-switches per
modulated frequency.
2.1.3. Microwave carriers are present and setup
properly.
2.2. Check RMAS-120 Receiver for the following:
2.2.1. Receiver shelf is grounded to the equipment
rack. Use power connector ground. The chassis
ground is not enough. The chassis is isolated from
the circuit board ground. Proper grounding is very
important.
2.2.2. DC Power is applied and main switch is ON.
2.2.3. AGC + and AGC – wiring is using shielded
twisted pair from the RMAS receiver to the microwave
radio AGC or RSL voltage points. The shield must be
grounded at the RMAS receiver end, minimum.
Grounding the shield to the rack is normal. Refer to
figure 3.2 in the manual.
2.3. Check the polarity of the AGC + and AGC –
inputs. Try reversing the polarity. The data is polarity
sensitive, one direction will synchronize and the other
will not.
3. Signal Measurements
3.1. Signal measurements are important to
determine if all equipment and connections are in
working order. Refer to the table of reference
waveforms.
3.2. Start at the RMAS-120 receiver unit.
Measure the waveform at the RCVR DATA test point
on the front panel. Waveform #7 should be found.
Waveform #8 shows the RX input signal and RCVR
DATA signals. A quick test can be made with a DVM
set to AC. Signal presence normally measures 2.3 ~
3.0 VAC. This quick test does not distinguish between
signal and AC Line noise.
3.2.1. To confirm the measured signal actually
comes from the RMAS transmitter, have another
person go to the RF repeater site and turn off the
RMAS-120 transmitter power switch. If the signal
goes away when the transmitter is OFF and comes
back when the transmitter is ON, then the alarm
telemetry data is really getting to the receiver.
3.2.2. If the signal is present, look at the signal on
the oscilloscope. Look for signs of interfering signals
such as AC power line hum and noise. Power line
frequencies, 50 Hz, 60 Hz, are close to the frequency
range of the telemetry data and will often cause
synchronization problems. Grounding and shielding
are the best ways to reduce AC interference.
Waveform #9 shows strong 60Hz AC interference.
3.3. RF. The next place to measure the
telemetry signal is at the RF repeater’s output. The
complete test requires a spectrum analyzer that
covers the radio carrier frequencies. A quick test can
be made using an RF power meter.
3.3.1. Quick test. Connect the RF power meter to
the RF MON SMA test port on the amplifier being
modulated by the alarm telemetry signal. This is the
same point used to set the RF output level.

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
Peninsula Engineering Solutions may change specifications as necessary to meet industry requirements. © 2014 Peninsula Engineering Solutions, inc.
Peninsula Engineering Solutions, inc. Telephone [phone]
POB 1095 Facsimile [phone]
Danville, California 94526, USA Internet www.peninsulaengineering.com
3.3.2. If the alarm telemetry signal is modulating
the carrier, the power meter needle or digital display
will wiggle or show a few tenths of dB change.
3.3.3. Turn OFF the RMAS-120 transmitter and
then ON again to see the change in pattern. If no
change is seen, check modulation switch settings and
wiring harness connections.
3.3.4. Complete test. Connect the spectrum
analyzer to the RF MON SMA test port on the
amplifier being modulated by the alarm telemetry
signal. Tune the analyzer to the microwave carrier
frequency.
3.3.5. When the carrier frequency is found, reduce
the frequency span to 0 (Zero) Span. This puts the
spectrum analyzer into time-base mode much like an
oscilloscope. Set the time-base to 10 msec/div if
possible. Waveform #6 should be displayed. Again,
turn the RMAS-120 transmitter OFF, then ON to see
the difference. If no change is seen, check
modulation switch settings and wiring harness
connections.
3.3.6. Make sure the correct microwave carrier
frequency is being modulated. If in doubt, switch ON
all frequencies equipped.
3.3.6.1. Note: in the case of tandem RF
repeaters, turning ON all frequencies can cause
telemetry interference with other RF repeaters if
two or more data streams are modulated on the
same carrier frequency.
3.4. Modulation. If the microwave carrier is not
modulated when it should be, check the telemetry
signal at the amplifier’s power connector or feed-thru
connections. Waveforms #3, 4 or 5 should be
observed.
3.4.1. Amplifier power connector pins.
Pin Signal/Feed-Thru Color
8 DIFF + VIO
7 DIFF - BRN
3.4.2. If the correct telemetry signal is present at
the amplifier power connector and RF carrier
modulation is not present, the amplifier must be
replaced.
3.5. RMAS-120 Transmitter. If the correct
telemetry signal is not observed at the amplifier
connector per 2.4, then measure the output of the
RMAS-120 transmitter unit.
3.5.1. Two locations can be used to confirm the
RMAS-120 transmitter alarm telemetry signal. J3, the
User Output connector on the lower side of the
RMAS-120 transmitter unit and TP1 and TP2 internal
to the unit.
J3 is easily accessible but requires a thin probe or
wire to fit the DB37-pin female connector.
J3-25, DIFF +
J3-26, DIFF -
J3-37, GND
TP1 and TP2 are located on the PCB under the black
cover panel. The black cover panel is removed by un-
snapping it from 4 posts. Look for TP1 and TP2 in the
upper right corner above the A and B Battery long
test points, T19, T20.
TP2, DIFF +
TP1, DIFF -
T1, GND
Waveforms #3, 4 and 5 should be observed.
3.5.1.1. Note: These points have a DC bias
between +2.5 ~ +4.0V. The RMAS-120
transmitter output is DC coupled to the amplifier
modulation inputs.
3.5.2. If the alarm telemetry signal is present but
not at the correct level, it is permissible to adjust pot
R58 for the correct level. Note the setting before
making an adjustment in case something goes wrong!
4. Fading
4.1. Fading of the microwave path can cause
interruption in the detection of the alarm telemetry
signal. Because the alarm telemetry signal occupies
the same frequencies as natural fast fading, when
deep fades or rapid fades occur, the receive can loose
frame synchronization. When fading subsides, the
receiver re-acquires frame sync and alarm telemetry
is received again.
4.1.1. Some microwave paths experience nearly
constant fading. These paths may be near coastal or
ocean areas where a strong maritime layer is often
present. In these cases, contact Peninsula
Engineering Solutions for alternate alarm transmission
equipment (UHF Radio Link).

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
Peninsula Engineering Solutions may change specifications as necessary to meet industry requirements. © 2014 Peninsula Engineering Solutions, inc.
5. Interference
5.1. Interference from AC Power Lines, hum and
noise, can be severe causing total loss of frame
synchronization or partial causing data errors. Section
2.2 covers the severe case.
5.1.1. When the interference is partial, it is possible
to have frame sync (SYNC LOSS LED is clear) and not
correctly receive alarms and telemetry. The
RMAS-120 receiver incorporates a data redundancy
check where each alarm must have the same data bit
for three frames before a change of state is
recognized. Partial interference can prevent three (3)
good data bits from being received thus preventing a
change of alarm state. Normally improvements to the
grounding and wiring between the RMAS-120 receiver
and the radio receivers will correct this problem.
Peninsula Engineering Solutions, inc. Telephone [phone]
POB 1095 Facsimile [phone]
Danville, California 94526, USA Internet www.peninsulaengineering.com
6. Incompatible AGC
6.1. Radios with incompatible AGC normally are
in these categories:
•AGC time constant is too slow
< 100dB/Sec
•AGC sensitivity (V/dB) is too low
< 20mV/dB
•AGC bandwidth is too low
< 100 Hz
•AGC voltage is not accessible
6.2. Since radios are designed differently, the
concepts used are not within the control of Peninsula
Engineering Solutions. Radios that have a digitized
AGC or derive the RSL monitor from a digitized AGC
typically are in one or more of these categories.
6.3. Alternative alarm transmission equipment
has been designed by Peninsula for these cases. The
alternate method uses a separate radio channel,
typically UHF, to transport the alarm telemetry data.
This method is completely independent from the main
microwave radio equipment.
7. Telemetry Inoperative, Receiver Unit
7.1. If the telemetry outputs of the RMAS-120
receiver are not reading correctly, where Battery A
shows nearly 0 volts and Battery B shows a steady
4 volts ±, there may be a physical problem in the
receiver unit.
7.2. Turn off the receiver, and remove the wires
connecting to all the connectors on the rear panel.
Remove the faceplate by unscrewing the 2
thumbscrews.
7.3. Observe the small D/A “daughter board”
mounted behind the Battery Voltage test jacks. It
should be oriented with the notch facing forward and
around the plastic spacer.
7.4. If this daughter board is reversed (notch to
the back and overhanging the MCU) then it will not
function correctly.
7.5. If the board is reversed, slide out the
receiver PCB and then pull out the D/A daughter
board from its socket. Orient the board so the notch
is forward and re-insert into the socket. See the
picture in Figure 1 below.
Figure 1 D/A Daughter Board, correctly installed
7.6. We have found that reversing the D/A board
normally does not damage it. Expectations are that
once correctly installed, the telemetry outputs will
function correctly. Should this not be the case, and
the receiver does not function correctly after correctly
installing the D/A board, contact Peninsula
Engineering Solutions for RMA support.
7.7. Slide the main receiver PCB inside the shelf
housing, attach the front panel and reconnect the
wires and connections to the rear panel connectors.
7.8. Apply power, turn on the receiver and check
out the telemetry outputs by measuring the voltages
at the front panel test jacks.

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
Peninsula Engineering Solutions may change specifications as necessary to meet industry requirements. © 2014 Peninsula Engineering Solutions, inc.
Peninsula Engineering Solutions, inc. Telephone [phone]
POB 1095 Facsimile [phone]
Danville, California 94526, USA Internet www.peninsulaengineering.com
8. Temperature Sensor
8.1. The battery temperature sensor or
transducer is used to measure the site storage
battery temperature to better estimate its state of
charge. The temperature sensor must be located near
or in contact with the site batteries. Typically, the
sensor is wedged between two batteries or supported
with a piece of foam insulation.
8.2. If the temperature reading disagrees with
the actual temperature (use a thermometer, don’t
guess!) or if the sensor has been replaced, it may be
necessary to re-calibrate the sensor.
8.2.1. Adjust pot R73 to calibrate the sensor.
Measure the voltage at T18. Use the following table
as a guide.
Temperature, °C/°F T18 Voltage
30C / 86F 3.50
29C / 84F 3.45
28C / 82F 3.40
27C / 81F 3.35
26C / 79F 3.30
25C / 77F 3.25
24C / 75F 3.20
23C / 73F 3.15
22C / 72F 3.10
21C / 70F 3.05
20C / 68F 3.00
19C / 66F 2.95
18C / 64F 2.90
17C / 63F 2.85
16C / 61F 2.80
15C / 59F 2.75
10C / 50F 2.50

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
Reference Waveforms
Use an oscilloscope to observe the data waveforms. Set the time-base to 10ms/div or 20ms/div. An oscilloscope with 2-channels
operating in A-B differential mode can be very useful in certain measurements. Signal bandwidths are quite low, ranging from
DC to 1 kHz. Waveform #6 requires a spectrum analyzer.
# Location Waveform Note: all drawn waveforms have the same time scale
1 RMAS-120
Transmitter
Data Timing
96b/frame
34b/s
29 msec per bit
5 data bits
2 RMAS-120
Transmitter
Manchester
Coded Digital
Data
29 msec per bit
s5 data bit
3 RMAS-120
Transmitter
LP Filtered
Data +
TP-2 to
Ground
2.5 ~ 4.0 V
DC Bias
Oscilloscope B Channel
20 msec/div, 1 V/div
DC Coupled
1.0 V P-P
4 RMAS-120
Transmitter
LP Filtered
Data -
TP-1 to
Ground
2.5 ~ 4.0 V
DC Bias
Oscilloscope B Channel
20 msec/div, 1 V/div
DC Coupled
1.0 V P-P
1 01 10
29 ms 29 ms 29 ms 29 ms29 ms

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
5 RMAS-120
Transmitter
LP Filtered
Data
TP-2 & TP-1
Amplifier
DIFF + &
DIFF -
Differential
Signal ntial Signal
A Channel = Data +, (DIFF +)A Channel = Data +, (DIFF +)
B Channel = Data –, (DIFF -)B Channel = Data –, (DIFF -)
10 msec/div, 1 V/div10 msec/div, 1 V/div
DC CoupledDC Coupled
1.0 V P-P each, 2.0 V P-P Differential
1.0 V P-P each, 2.0 V P-P Differential
6 Microwave
Amplifier
RF MON,
Amplitude
Modulated
1.0 ± 0.3 dB P-P
7 RMAS-120
Receiver
RCVD DATA
TP to GND
Oscilloscope B Channel
20 msec/div, 2 V/div
DC Coupled
5.0 V P-P

Part Number: 650-1020-01
Revision B1
December 2014
Technical Note
8 RMAS-120
Receiver
Input Data to
Receiver
RCVD DATA
TP to GND
RCVD DATA
TP to GND
A Channel = Input Signal and NoiseA Channel = Input Signal and Noise
50 mV/div, 20 msec/div50 mV/div, 20 msec/div
B Channel = RCVD DATA TP to GNDB Channel = RCVD DATA TP to GND
2 V/div, 20 msec/div
2 V/div, 20 msec/div
9 RMAS-120
Receiver
60Hz AC
Interference
on RCVD
DATA
TP to GND
Oscilloscope B Channel
10 ms/div, 2 V/div
5.0 V P-P
Note the shorter waveform period of AC
60Hz = 16.7 msec.
50Hz = 20.0 msec period.