Pira PIRA75 User manual

PIRA75 / P175
FM Broadcast Analyzer
User Manual
Firmware version 1.5 rev. 2
Web: http://www.pira.cz E-mail: m[email protected]

2
Table of Contents
Related Documents...........................................................................................................................................................2
Introduction ......................................................................................................................................................................3
Main highlights...................................................................................................................................................................................3
Measurements, indications and outputs...............................................................................................................................................3
Technical Specifications...................................................................................................................................................4
Power supply (P75).............................................................................................................................................................................6
Power supply (P175)...........................................................................................................................................................................6
Mainboard composition (P75).............................................................................................................................................................7
Mainboard composition (P175)...........................................................................................................................................................8
Alarm outputs (P175)..........................................................................................................................................................................9
Operating Instructions ...................................................................................................................................................10
Power-up...........................................................................................................................................................................................10
Control buttons..................................................................................................................................................................................10
Operating modes ...............................................................................................................................................................................10
Menu.................................................................................................................................................................................................10
Measurements.................................................................................................................................................................12
Signal quality ....................................................................................................................................................................................12
Overall frequency deviation (peak frequency deviation)...................................................................................................................14
Pilot deviation...................................................................................................................................................................................14
RDS deviation...................................................................................................................................................................................14
Pilot-to-RDS phase difference...........................................................................................................................................................15
Modulation power (MPX power, Pm)................................................................................................................................................15
Frequency deviation histogram.........................................................................................................................................................16
Service details (P75) .........................................................................................................................................................................17
Service details (P175) .......................................................................................................................................................................17
Simple stereo balance meter..............................................................................................................................................................17
Carrier frequency offset ....................................................................................................................................................................18
Radio Data System decoding ............................................................................................................................................................19
USB and COM Port Communication ...........................................................................................................................23
Connecting the FM analyzer to a PC.................................................................................................................................................23
List of commands and configuration registers...................................................................................................................................23
Service Part .....................................................................................................................................................................28
Firmware update ...............................................................................................................................................................................28
Superheterodyne receiver ganging....................................................................................................................................................28
Annexes............................................................................................................................................................................29
Memory map.....................................................................................................................................................................................29
Related Documents
Visit the Website for the latest documentation version and the following additional documentation:
FM Scope - User Guide (http://pira.cz/fm_broadcast_analyzer/fmscope.pdf)
RDS Spy - RDS Decoder for Windows (http://rdsspy.com/download/mainapp/rdsspy.pdf)

3
Introduction
The P75 and P175 FM Broadcast Analyzer is a stand-alone low-cost solution for FM broadcast analysis.
It provides complete FM modulation and basic AF spectrum measurements in FM radio band through the
antenna input.
Built-in LCD display and control interface allows to measure and collect data in terrain without need of
any PC computer. Serial interface and the control software provide a possibility of remote control, data
viewing and automated data logging.
This kind of analyzer is essential equipment for all FM radio stations to ensure compliance with basic
technical broadcast standards and to accomplish the highest audio quality possible.
Main highlights
Stand-alone design, completely DSP based from IF to outputs
Compliant with CEPT/ERC REC 54-01 E and ITU-R SM.1268
Dual-conversion receiver
Built-in LCD display and RS-232 interface
Built-in USB interface (P175)
Firmware updates are free
Easy to use
Measurements, indications and outputs
Overall frequency deviation incl. histogram
Modulation power (MPX power)
Baseband spectrum, RF carrier spectrum
Pilot deviation
RDS deviation
Pilot-to-RDS phase difference
FM carrier frequency offset
Reception quality and signal strength
Stereo balance meter
Headphones audio output
Alarm logic or general purpose outputs (P175)
RDS/RBDS decoder
Please read this entire manual and familiarize yourself with the controls before attempting to use this equipment.
The equipment has been thoroughly tested and found to be in proper operating condition when shipped. The
manufacturer is not liable for any damages, including but not limited to, lost profits, lost savings, or other incidental or
consequential damages arising out of the use of this product.
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying, recording or information storage and retrieval systems, for any purpose other than the
purchaser's personal use.
It is our intention to provide you with the best documentation possible to ensure successful use of the product. If you
wish to provide your comments on organization, clarity, subject matter and ways in which our documentation can better
serve you, please mail us your comments.
Information in this document is subject to change without notice.
Revision: 2016-10-05
Copyright © 1999-2016 Pira.cz

4
Technical Specifications
Parameter
Condition
Value
General
Supply voltage (P75)
external
8 –16 V DC
battery
4.8 –5.8 V DC (4x AA NiMH)
Supply current (P75)
LCD off
170 mA
LCD on
240 mA
Supply voltage (P175)
external
8 –12 V DC
battery
2.3 –4.5 V DC (2x or 3x AA NiMH)
USB
5.0 V
Supply current (P175)
LCD off
140 mA
LCD on
210 mA
battery
up to 500 mA
External power supply connector
DC 2.1 mm
Board dimensions (P75)
139 x 72 mm
Board dimensions (P175)
133 x 70 mm
CPU
120 MHz RISC DSP
Data connector (P75)
RS-232 (DCE, 9 pins), bidirectional
Data connector (P175)
RS-232 (DCE, 9 pins), bidirectional,
USB (FTDI based, virtual serial port)
Communication speed
19200 bps
Communication mode
1 stop bit, 8 data bits, no parity, (no flow control)
RX buffer length
40 bytes
Intermediate frequency (IF)
1st IF
10.675 MHz
2nd IF
0.325 MHz ±0.005 MHz
IF bandwidth
280 kHz
Antenna Input
Antenna connector
BNC, 50 Ohms
Frequency range
87.5 –108.0 MHz
Tuning step
selectable 50 kHz or 100 kHz
Input sensitivity
S/N 26 dB
4 μV
basic measurements
30 μV
full measurements
70 μV
Maximum input level
0.5 V (5 mW)
Intermodulation immunity
basic (single input LC circuit with coil tap)
Never connect RF power output from the transmitter directly to the device's antenna input!

5
Measurements
Frequency deviation range
min.
0 –121 kHz
Frequency deviation error
1 kHz sine
< ± 1.5 kHz
typical content
< ± 2 kHz
Modulation power range
min.
-12 –14 dBr
Modulation power error
-6 –6 dBr
± 0.2 dBr
Pilot deviation error
6.8 kHz
± 0.2 kHz
RDS deviation range
1.0 –17.9 kHz, note 5
RDS deviation error
full signal
± 5% ± 0.5 kHz
Pilot-to-RDS phase difference error
± 4 deg.
Baseband frequency response flatness
10 Hz –60 kHz
± 0.3 dB
Stereo balance error
± 0.5 dB
Signal level error (P175)
35 –86 dBµV
non-linearity ± 3 dBµV, offset ± 2 dBµV
0 –35 dBµV
not specified
Alarm Outputs (P175)
Maximum current from pin 1
100 mA
Maximum current from/to pin 2, 3, 4, 5
15 mA (internally limited by 390R serial resistor)
Headphones Audio Output
Audio channels
1 (switchable R+L, L, R, R-L)
Output impedance
typ.
100 Ohms
Output level
no load
adjustable 0 –2.5 V p-p @ 75 kHz
Signal to noise ratio
75 kHz, volume 0 dB
55 dB
Stereo decoder separation
1 kHz
>23 dB
Distortion
1 kHz
2 %
Internal RDS/RBDS Decoder
RDS groups detected
All RDS groups 0A-15A, 0B-15B
RDS services supported
PS, PI, PTY, PTYN, TP, TA, M/S, DI, AF, EON,
ECC, LIC, PIN, RT, CT, AID, RT+
RDS groups decoded
0A, 0B, 1A, 2A, 2B, 3A, 4A, 10A, 14A
RDS deviation (ΔFrds) required
min.
1.0 kHz
Antenna input sensitivity
(average BER = 5 % or less,
single station, no interference)
ΔFrds=2.0 kHz
30 μV
ΔFrds=3.4 kHz
18 μV
ΔFrds=6.8 kHz
9 μV
Never exceed specified voltage value at the battery power supply connector! It may cause
permanent damage to the device! Disconnect or remove accumulators from the unit when it is
not in use!
Don’t open the plastic cover (boxed versions)! No user adjustable parts inside! Risk of damage!
Take care to avoid strong mechanical pressure on the power switch during transport!
Never use the equipment if there's any visible damage on its electrical parts! In that case
disconnect all cables, remove accumulators and contact the vendor or manufacturer.

6
Notes (Technical specifications):
1. p-p = peak-to-peak value; BER = Block Error Rate
2. Due to inherent reception the unit may have reduced sensitivity at 90.0 MHz.
3. Very strong el. field intensity (above 130 dBμV/m) may cause additional measuring error or may disallow
the measurement.
4. Shadowed fields are device specific.
5. If pilot and RDS are not synchronized, the range reduces to 1.7 –17.9 kHz. Spurious RDS detection may
occur on stations without RDS if the station's signal is noisy or specific static sine tones are transmitted.
If ARI system is used simultaneously with RDS on the same transmitter, the RDS deviation value should
not be taken into consideration. Instead of this the Windows application and MPX spectrum graph gives an
image about signal level of each component.
Power supply (P75)
External power supply connector
The FM analyzer can be supplied from any power supply, which delivers a voltage between 8 and 16 V DC and
continuous current of 300 mA to 1 A. The FM analyzer has polarity protection and own voltage stabilizer. The
central conductor of the power supply connector is positive (+).
Battery power supply connector
Use this connector for supplying the FM analyzer from 4x 1.2V NiMH accumulator or stabilized +5V power supply.
This connector is polarity protected.
If both power supply connectors are being used to power the FM analyzer, the external connector has higher
priority.
The unit does not charge the battery.
Power supply (P175)
External power supply connector
The FM analyzer can be supplied from external power supply (typically DC wall adapter), which delivers a voltage
between 8 and 12 V DC and continuous current of 300 to 500 mA. The FM analyzer has polarity protection and own
voltage stabilizer. The central conductor of the power supply connector is positive (+).
Battery power supply connector
Use this connector for supplying the FM analyzer from 2x or 3x 1.2V NiMH accumulator.
Due to safety reasons, the unit does not charge the battery.
USB connector
Use this connector for supplying the FM analyzer from PC computer or stabilized +5V power supply.
This connector is not polarity protected. Connecting an active USB cable the unit is always turned on, i.e. the power
off/on switch has no effect if the unit is powered from USB.
Never exceed specified voltage value at this connector! It may cause permanent damage to the
device!
The USB port must be rated to full 500 mA current! When supplying the unit from USB bus, it is
a better choice to connect the unit to the USB interface on the main board. Supplies for pocket
USB hubs and for some USB interfaces of lap-top and desk top computers are not sufficient and
an external power supply is necessary!

7
Mainboard composition (P75)
J1 –LCD display connector (HD44780 standard)
J2 –Expansion IIC bus
1: +5 V
2: SDA
3: SCL
4: Ground
J3 –Reserved for user applications
1: Ground
2: DIP5 output (for remote switching)
3: Reserved
4: Ground
5: +5 V
J4 –Reserved
1: MPX/audio PWM output (no LPF)
2: Receive Data (RxD), TTL
3: Transmit Data (TxD), TTL
J5 –Battery power supply connector
J6 –Audio connector mono/stereo switch
1-2: mono jack
2-3: stereo jack (headphones)
Note: the audio output is still one channel.
LCD module connection (if flat cable is used)
Make sure the LCD module is connected right before connecting power supply!
Incorrect connection will cause permanent damage to the LCD module.

8
Mainboard composition (P175)
J1 –Alarm outputs / General purpose outputs *
1: +5 V output for powering external device
(max. 100 mA)
2: Alarm 1 (Signal lost)
3: Alarm 2 (Silence)
4: Alarm 3 (Overmodulation)
5: Alarm 4 (Pilot or RDS level error)
6: Ground
J2 –Reserved for special applications
1: DIP5 output (for remote switching)
2: Reserved
3: Ground
J7 –Battery power supply connector
J10 –External buttons (pull-up resistors on board)
1: Ground
2: Up
3: Down
4: OK
J11 –Serial RS-232 port (TTL levels)
1: Receive Data (RxD)
2: Transmit Data (TxD)
3: Ground
* Notes:
The Alarm outputs can be used as independent general purpose logical outputs. See the section "List of commands
and configuration registers" for more details.
Maximum current from/to pins 2-5 is limited by internal 390R serial resistors.
Note: The device provides three serial communication ports (USB, RS-232 and J11). These ports are internally
linked together so the user may select any of these ports that best fits the communication requirements. When
requesting data via any port, all ports will send the reply. The user must ensure that different ports will not receive
requests at the same time.
Note for boxed version: There are no user-adjustable elements inside! Don’t remove the front panel!

9
Alarm outputs (P175)
The device provides four independent logic outputs that are set by specific alarm conditions. These outputs can be
used for direct LED driving, switching to backup transmission equipment, signalizing via GSM gateway etc.
The alarm outputs are active high. If the alarm condition is no longer actual, appropriate output is driven low when
the time hysteresis elapses. Almost all parameters are user configurable. With factory default values the alarm
behavior is as showed in this table:
Alarm output
Condition
Interpretation
Alarm 1:
Signal lost
Signal quality < 4
(time duration 30 seconds)
FM transmitter failure or signal for the P175 device
is too weak for permanent monitoring.
Alarm 2:
Silence
ΔF AVE < 25 kHz
(time duration 1 minute)
There's no audio or the audio level is too low.
Broadcast automation system has crashed or
studio's mixing console has been set improperly or
connection between studio and transmitter has been
lost.
Alarm 3:
Overmodulation
ΔF MAX Hold > 88 kHz
and
[Histogram Max At > 78 kHz
or
ΔF AVE > 78 kHz]
(time duration 1 minute)
Transmitter problem or sound processing problem
or unauthorized manipulation with the broadcast
equipment or signal too bad (alarm 1 interpretation
may apply).
Alarm 4:
Pilot or RDS level error
ΔF Pilot < 5.8 kHz
or
ΔF Pilot > 7.7 kHz
or
ΔF RDS > 8.5 kHz
(time duration 1 minute)
Stereo encoder fault or transmitter problem or
unauthorized manipulation with the broadcast
equipment.
The device must operate in Measuring mode otherwise alarms are deactivated and the outputs are driven low. The
user must ensure that the device will receive the station's signal in appropriate quality. To resume the monitoring on
desired frequency automatically after eventual power drop out, save the settings using menu item 4. To configure
the alarms see the section 'USB and COM Port Communication'.
Alarm response example.
Application example –Logical sum (OR function) of alarm outputs.

10
Operating Instructions
Power-up
For external power supply, make sure the unit is switched off. Connect the power supply and then switch the unit
on. The device requires no heating time. After a few seconds the unit is ready for operate. The antenna, audio and
data cables can be connected regardless of the operating state.
Control buttons
Button
Meaning

Go to next page or menu item, tune up.

Go to previous page or menu item, tune down.
OK, enter the menu, confirm or change the option.
Operating modes
Measuring ON
Measuring OFF
RDS decoder mode
Stereo decoder mode
L
R
L-R
L+R
The mode selected is indicated at the first line of the LCD. When switching between the modes, the values measured
will remain. The stereo decoder modes affect the audio signal in headphones output. This output is one-channel.
Menu
To enter the menu, press the OK button. Some items are showed depending upon context (page or operating mode).
Menu item
Meaning
1 –Tune
Tune to a desired frequency in FM band (manual tuning)
2 –Scan
Tune using a scan mode (automatic tuning, stops on each station).
3 –Histogram Data
3 –Set as Normal
3 –More RDS Data
Show frequency deviation histogram values.
Consider the 2nd IF as a normal (see Carrier frequency offset)
Show more Radio Data System information.
4 –Save Settings
Save settings (incl. actual frequency tuned)
5 –Save Data
Save measured data and RDS data into EEPROM.
6 –Load Data
Load measured data and RDS data from EEPROM.
7 –Clear Data
Clear all measured values in operational memory.
8 –Volume
Adjust audio volume in steps.
9 –Sending Pm
9 –Mode
Enable/Disable sending of modulation power values via serial port if measuring is
enabled.
Set the operating mode if measuring is OFF: RDS, Stereo L, R, L-R, L+R.
10 –Measuring
Enable/Disable the measuring.
11 –Return
Return from the menu.