Rhotheta RT-1000 User manual

User Manual
RT-1000 Multichannel
DF-Channel

RT-1000 MC DF-Channel
RHOTHETA Page 2 of 27 User Manual
Edited by:
RHOTHETA Elektronik GmbH
Kemmelpark
Dr.-Ingeborg-Haeckel-Str. 2
82418 Murnau
Germany
Tel.: [phone] - 0
Fax: [phone] - 15
Internet: www.rhotheta.de
E-Mail: [email protected]
Copyright © RHOTHETA Elektronik GmbH
All rights reserved
-Issue: 2016/11/08 [Rev 1.02.a]
-Document-ID: 12-9-1-0015-10-1-3-1-60
Note
The manufacturer reserves the right to make modifications at any time and without previous
information of the here described product.

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Content
1 Description.......................................................................................................................5
2 Front View ........................................................................................................................5
3 Block Diagram and Component Description.................................................................6
4 Control Elements.............................................................................................................8
5 Rear View..........................................................................................................................9
6 Functional Descriptions................................................................................................12
6.1 Switching on the DF-Channel...............................................................................................................12
6.2 Switch-on Reaction, Operation, Control Equipment.............................................................................12
6.3 Receiver Self-Test................................................................................................................................12
6.4 Power Supply OK Control LED.............................................................................................................12
6.5 Control Data Transmission...................................................................................................................12
6.6 Squelch Control LED “Sql” ...................................................................................................................12
6.7 Bearing Indication.................................................................................................................................12
6.8 ∆f-, ∆f+ Deviation Recognition Control LEDs.......................................................................................13
6.9 Control LED “No Sync”.........................................................................................................................13
6.10 “IF” Intermediate Frequency Jack.........................................................................................................13
6.11 Remote / Local Switch..........................................................................................................................13
6.12 “Level-Frequency-QDR” Switch............................................................................................................13
6.13 Frequency Selection key ▲/▼.............................................................................................................13
6.14 Squelch adjustment potentiometer.......................................................................................................13
6.15 Phase Adjustment.................................................................................................................................14
6.15.1 Adjustment Using RTM 1500 Antenna Model (Option)..........................................................14
6.15.2 Adjustment Using a Transmitter.............................................................................................14
6.16 Error Indication .....................................................................................................................................15
6.17 "Sync" Synchronisation Indicators........................................................................................................15
6.18 "DF Signal 2" Test Plug........................................................................................................................15
6.19 "R/L" Test Connector............................................................................................................................15
6.20 Serial Interface......................................................................................................................................16
6.21 Data Output ..........................................................................................................................................17
6.22 Data Input .............................................................................................................................................19
7 Electrical Parameters ....................................................................................................22
7.1 Power Supply........................................................................................................................................22
7.2 DF-Signal 2 and R/L.............................................................................................................................22
7.3 Reference Signals Input .......................................................................................................................23
7.4 Pegel- Output........................................................................................................................................24

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7.5 AM – Output..........................................................................................................................................24
7.6 FM – Output..........................................................................................................................................24
7.7 PHI – Output.........................................................................................................................................25
7.8 AF – Output ..........................................................................................................................................25
8 Mechanical Parameters.................................................................................................26
9 Notes...............................................................................................................................27

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1 Description
The DF-Channels are the central element of the bearing system. The channels include the
receiver unit with the signal demodulation for AM and FM signals. Also the bearing value
calculation is done in the DF-Channels.
2 Front View
Fig. 1: DF-Channel Front View

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3 Block Diagram and Component Description

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DF
-
Channel Components
Pos.
Component
Number
Description
1 Receiver RTR-1204
Receives the RF signal from the RF-Splitter.
Demodulates the AM and FM signals and
generates the bearing phase.
2 Receiver Interface RTR-1205
The Receiver Interface controls the receiver
unit. It is the communication interface
between the receiver and the CPU.
3 Frequency Processing RTC-1107
The Frequency Processing unit include
components for filtering the audio signal. It
also generates the reference clock out, which
is needed for phase meter out of antenna
control signals (6.144 MHz and R/L – Puls)
4 Bearing Filter RTC-1105
The Bearing Filter unit includes the
components for bearing filtering, bearing
signal synchronization and a circuit to detect
an evaluable bearing signal.
5 Phase Summator RTC-1109
The Phase Summator unit is used to average
the phase of the bearing phase signal before
it is processed by the phase meter.
6 Phase Meter RTC-1106
The Phase Meter unit includes the
components for determining the phase
position of the demodulated bearing signal
relative to the reference phase. The result is
the averaged bearing data and also life
bearing data, which is process by the CPU.
7 CPU RTC-1104
The CPU contains a microprocessor which
controls the assemblies in the DF Channel.
The CPU also serves the serial interface,
which provide the bearing data and allows
the remote control of the DF Channel.
8 Audio Power RTX-1402
The Audio Power unit includes the power
switch of the DF Channel, the micro fuses for
the DC supplies and the speaker with a
volume control.
9 F1 -- Microfuse T1.0A 250V 5x20mm, +5 V DC
10 F2 -- Microfuse T0.5A 250V 5x20mm, +15 V DC
11 F3 -- Microfuse T0.16A 250V 5x20mm, -15 V DC

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4 Control Elements
Front Side Interfaces
Pos.
Component
Description
12 IF Receiver test jack
13 Pow Receiver Power Control LED
14 Sql Control LED for receiver squelch
15 Frequency(MHz)
Sql/(Level) Receiver Display
16 ∆f- Control LED for negative frequency deviation
17 ∆f+ Control LED for positive frequency deviation
18 ▲Button for upward frequency change in local mode
19 No Sync Control LED for receiver synchronisation error detection
20 Remote/Local Switch remote operation or manual for test purpose
21 ▼Button for downward frequency change in local mode
22 Sql-Pot Squelch adjustment potentiometer
23 Frequency
Sql(Level)/QDR Receiver display
24 Band Button to switch between marine and air band (optional)
25 Sync
o.k. Control LED: synchronization ok, green
26 Sync
Err. Control LED: synchronization not ok, red
27 Test: DF-Signal 2 Test Plug, DF signal (filtered)
28 Test: R/L Test Plug, R/L signal
29 Phase-Adj: coarse Rotary switch for coarse phase adjustment
30 Phase-Adj: fine Rotary switch for fine phase adjustment
31 Phase-Adj: o.k Control LED for phase adjustment
32 Volume Volume control for the Speaker (pos 31)
33 +5 V
Power control LED for the 5 V
DC
Green: Power on
Red: Fuse defect
Off: No Supply Voltage/ DF Channel Off
34 +15 V
Power control LED for the +15 V
DC
Green: Power on
Red: Fuse defect
Off: No Supply Voltage/ DF Channel Off
35 -15 V
Power control LED for the -15 V
DC
Green: Power on
Red: Fuse defect
Off: No Supply Voltage/ DF Channel Off
36 On/Off DF Channel Power switch. All DC supplies are switched together.
37 Speaker Adjustable audio output for each channel

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5 Rear View
Fig. 2: DF-Channel Rear View

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Rear Side Interfaces
Pos.
Connector
Pin
Signal
Note
1 X1 1 – 4 RF-IN RF Input from the RF-Splitter
5 – 29 -- Internal Connector
2 X2 1 – 32 -- Internal Connector
3 X3 1 – 32 -- Internal Connector
4 X4 1 – 32 -- Internal Connector
5 X5 1 – 32 -- Internal Connector
6 X6 1 – 32 -- Internal Connector
7 X7 1 – 32 -- Internal Connector
8 X8 1 – 32 -- Internal Connector
9
X9
1 ROT-OFF IN Input Antenna Rotation Control Signal
10 2 GND Ground
11 3 ROT-OFF OUT Output Antenna Rotation Control Signal
12 4 GND Ground
13 X10 1 PTT Push to talk input signal
14 2 GND Ground
15
X11
1 GND Ground Power Input
16 2 -15 V - 15 V
DC
Power Input
17 3 +15 V +15 V
DC
Power Input
18 4 +5 V + 5 V
DC
Power Input
19 X12 (SMB) -- 6144kHZ IN Input Reference Signal 6,144 MHz
20 X13 (SMB) -- 6144kHZ OUT Output Reference Signal 6,144 MHz
21 X14 (SMB) -- R/L-PULS IN Input Reference Signal R/L-Pulse
22 X15 (SMB) -- R/L-PULS OUT Output Reference Signal R/L-Pulse
23 X16 (SMB) -- PEGEL Receiver Output Level Signal
24 X17 (SMB) -- PHI Receiver Output Bearing Phase Signal
25 X18 (SMB) -- AF Receiver Output Audio Signal
26 X19 (SMB) -- AM Receiver Output AM-demodulated Signal
27 X20 (SMB) -- FM Receiver Output FM-demodulated Signal
28 X21
(RJ 45)
3 GND RS-232, Ground
29 4 RX RS-232, Receiving Data
30 5 TX RS-232, Transmitting Data
31 X22 1 – 26 DIAGNOSIS
DISPLAY Service Interface
32 X23 (PDI) 1 – 6 REC-PDI Service Interface
33 X25 (BNC) -- AF-CONST Constant Audio Output
34 X24 (BNC) -- AF-VAR Adjustable Audio Output

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Rear Side Test Points
TP
Signal
Note
1 +5 V +5 V DC Supply after the channel power switch
2 +15 V +15 V DC Supply after the channel power switch
3 -15 V -15 V DC Supply after the channel power switch
4 6144 kHz Input of the Reference Signal 6.144 MHz
5 R/L-PULSE Input of the Reference Signal R/L-Pulse
6 6144 kHz Amplified Reference Signal 6.144 MHz
7 R/L-PULSE Amplified Reference Signal R/L-Pulse
8 RX AFC DC The AFC signal Level of the receiver
9 GND Ground
10 O TXD Internal signal, transmitted serial data
11 O RXD
12 RXDATA Serial Interface X21 receiving data
13 TXDATA Serial Interface X21 transmitting data
14 -15 V DC Power Supply -15 V Input
15 +15 V DC Power Supply +15 V Input
16 +5 V DC Power Supply +5 V Input
17 GND Ground
18 RS232-RX Internal signal, received serial data RS-232
19 RS232-TX Internal signal, transmitted serial data RS-232
20 GND Ground
21 CPU TXD Internal signal, transmitted CPU data
22 CPU RXD Internal signal, received CPU data
23 PSUM-SQU Squelch Signal of the Phase Summator
24 PFSQL DFSIG Bearing signal output of the bearing filter

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6 Functional Descriptions
6.1 Switching on the DF-Channel
The DF-Channel is switched on by the On/Off power switch. Ensure that all components are
completely inserted and the screws are in place.
The DF-Channel unit is designed for continuous operation. It must be noted that at low
temperatures a warm-up phase lasting up to 30 minutes may be possible after switching on
the receiver unit.
6.2 Switch-on Reaction, Operation, Control Equipment
The DF-Channel is designed for remote operation. The unit is operated by remote control
using the RHOTHETA DF-Commander software. All relevant control functions and indications
are transmitted to the remote PC via the serial interface to the DF-Control System which
converts the data to LAN. The indications and settings on the DF-Channel are present only
for test purposes and for carrying out function checks on the whole system.
6.3 Receiver Self-Test
After the DF-Channel has been switched on, an automatic test of the receiver display (Fig 1,
Pos.15) is started. This involves the numerical series 88888888 flashing for approximately 4
s. Following this, after that the system identification “RT-1000 A” is displayed and the actual
software version is shown for some seconds. When the self-test is finished the last frequency
set appears.
6.4 Power Supply OK Control LED
After switching on, the green control LEDs (Fig 1, Pos. 33, 34, 35) of the Power Supply
module RTX 1402 (Fig 1, Pos. 8) and (Fig 1, Pos. 13) on the receiver RTR 1204 (Fig 1, Pos.
1), lights up. This shows that the power supply module is functioning correctly.
6.5 Control Data Transmission
If the DF-Channel works in “Remote” mode (standard) the display (Fig 1, Pos. 15) shows the
set frequency. It indicates that the data connection between receiver unit and controller is
established. If the communication is disturbed, the error message “No Remote” is displayed.
6.6 Squelch Control LED “Sql”
The yellow squelch control LED (Fig 1, Pos. 14) lights up as soon as a signal of sufficient
strength is received. This shows that a bearing signal is being transmitted to the controller.
6.7 Bearing Indication
If the system receives a signal and calculates a bearing value , the bearing indicator at the
right side of the receiver display Figure 1 Pos. 15 lights up as a “*”.
If no signal is received, the indicator lights up every second as a “>”. If the PTT function is
active, the indicator lights up as a “_”.

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6.8 ∆f-, ∆f+ Deviation Recognition Control LEDs
The red control LEDs (Fig 1, Pos. 16 & 17) light up if a signal with a large frequency deviation
is received. This shows that a signal is being received which is not suitable for direction
finding purposes.
For the 25 kHz frequency channel scheme the control LEDs light up for a frequency deviation
> 8,0 kHz/ > 9,0 kHz typically.
For the 8,33 kHz frequency channel scheme the control LEDs light up for a frequency
deviation > 1,4 kHz/ > 2,7 kHz typically.
6.9 Control LED “No Sync”
In case of a PLL lock error the red LED “No Sync” (Fig 1, Pos. 19) illuminates. It indicates a
failure on the receiver unit RTR 1204.
6.10“IF” Intermediate Frequency Jack
The intermediate frequency signal supplied by the receiver can be tapped at the IF SMB jack
(Fig 1, Pos. 12).
Caution
Only for service use!
6.11Remote / Local Switch
•“Remote” position: Standard operation mode; Receiver controlled by Controller Unit.
•“Local” position: For test purpose the working frequency can be changed locally. In
this position the frequency DF Commander at the Controller side shows “ERR 9”.
6.12 “Level-Frequency-QDR” Switch
Standard position of the switch is “frequency”. The display (Fig 1, Pos. 15) shows the actual
frequency. In position “Level” the display shows the signal level (0..99 %, not calibrated). In
position “QDR” the display shows the actual bearing value.
6.13Frequency Selection key ▲/▼
At mode “local” it is possible to increase the frequency in 25 kHz steps by pressing the key ▲
(Fig 1, Pos.18) or decreasing the frequency in 25 kHz steps by pressing the key ▼(Fig 1,
Pos. 21).
If the option 8,33 kHz is active the frequency in-/decreases combined in the 25 kHz and 8,33
kHz channel scheme.
In accordance with ICAO Annex 10 Volume V clause 4.1.2.4. table 4.1 (bis).
6.14Squelch adjustment potentiometer
Behind the hole (Fig 1, Pos. 19) there is a potentiometer which allows a squelch adjustment.
For this, a small screw driver is necessary.
If turning clockwise the squelch threshold god down, counter clockwise the squelch threshold
rises.

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6.15Phase Adjustment
A special feature of the RT-1000 DF is its phase compensation by left / right rotation of the
antenna. This allows complete compensation of direction finding errors caused by signal
phase variations in the reception channel. However, it is only possible to compensate for a
limited phase value. For this reason, make a pre-adjustment to the centre of the variation
range.
The adjustment can be made either using the RTM 1500 Antenna Model or aligning of the
labelled antenna radiator (North dipole) onto a transmitter.
6.15.1 Adjustment Using RTM 1500 Antenna Model (Option)
•Connect the antenna model instead to the TEST-IN port of the RF-Splitter (see User
Manual of RTM 1501 Antenna Model).
•Feed in a VHF signal in the ATC band range with a signal level of approx. 100 mV at
the antenna model RF input and adjust the receiver to the appropriate frequency. Move
the antenna signal switch on the dummy antenna to the 180° position.
Note:
Since the direction finder was pre-set in the factory, the bearing display must show QDM 180°
and QDR 0° on condition that the north adjustment is set to 0°. QDM 0° and QDR 180° may
also be displayed if the phase is completely misaligned.
•Phase adjustment can be set using the two rotary switches, "fine" (Fig 1, Pos. 30) and
(Fig 1, Pos. 29) "coarse". The total of 256 steps (8 bit) on the coarse switch are divided
into 16 steps, and these coarse steps are sub-divided into a further 16 steps on the
fine switch. Use these rotary switches to find the middle of the range where the green
control LED (Fig 1, Pos. 31) lights up. The QDM display should then show 180°
(QDM).
6.15.2 Adjustment Using a Transmitter
Position a test transmitter (e.g. walkie-talkie) approx. 100 m away, exactly to the north of the
direction finder antenna (dipole north with label pointing towards the transmitter). The bearing
display should show QDM 180° and QDR 0°. The north adjustment on the controller should
be set to 0°. Phase adjustment is set.
Note:
The transmitter has to be exactly in the north of the antenna. The bearing display has to show
180° (or 000°). A deviation of more than ±1° will make it impossible to execute the phase
adjustment.

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6.16Error Indication
The equipment has a wide range of self-test devices. If an error is discovered, the error code
is shown flashing at 1 sec. intervals in the frequency display (Fig 1, Pos. 15).
Display: E R R 7
Error Indication
Error Code
Error Type
1 Processor
2 EPROM
3 RAM
4 Power Supply
5 EEPROM
6 Synchronisation
7 Phase Measurement
8 Data Transfer or Power Supply of the Receiver
9 Receiver Control
Caution
If an error message appears, the DF-Channel is no longer functional.
6.17"Sync" Synchronisation Indicators
The green indicator (Fig 1, Pos. 25) lights up if in the controller the electronics in the
Frequency Processing module RTC 1107 is synchronised with the reference signal from the
Antenna Control module RTR 1201.
The red indicator (Fig 1, Pos. 26) lights up if the above mentioned synchronisation is not
achieved.
When this indicator is on, it indicates the following possible malfunctions:
•Receiver unit not ready for operation (e.g. switched off)
•Data line defective
•RTR 1201 Antenna Control module defective
•RTC 1107 Frequency Processing module defective
6.18"DF Signal 2" Test Plug
The test signal for bearing determination is applied to the test connector (Fig 1, Pos. 27). The
signal can be monitored using an oscilloscope. It indicates the quality of the bearing value.
Plug type: SMB
6.19"R/L" Test Connector
The signal for changing over the fictitious antenna rotation from clockwise to counter-
clockwise is applied to the test plug (Fig 1, Pos. 28). This signal is used for triggering the
oscilloscope when monitoring the DF signal.
Plug type: SMB

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6.20Serial Interface
The serial interface RS-232 (Fig 2, X21) enables the transmission of bearing data to an
external control unit and also permits remote control from an external unit.
The characters to be transferred are transmitted in ASCII code from the CPU RTC 1104
Controller. The data bit sequence, which is assigned in each case to the characters to be
transmitted, is preceded by a start bit and followed by a stop bit. Both additional bits ensure
that both transmitter and receiver are time-synchronized.
The data traffic via the serial interface is in asynchronous mode. For time-synchronisation of
the data transmitter and receiver the data receiver is triggered by the rising edge of the start
bit at the beginning of the bit sequence of a character.
The transmission of a message begins with the header consisting of an alphanumeric
character. The actual message content forms a string of (ASCII) decimal numbers. The
transmission of a message is ended by the final identifier "CR" (decimal code 13) and “LF”
(decimal code 10).
The signal level on the data lines corresponds to the RS-232 standard, i.e. a high is defined
as a voltage between +3 V and +15 V and a low as a voltage between -3 V and -15 V. The
data is transmitted in negative logic.

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6.21Data Output
The data output is continuous, i.e. no control by means of a handshake signal or control characters is necessary.
Message Header Content
„Average“ bearing
(QDR-value) A X X X [CR][LF]
││└───────────────>
│└─────────────────>
└───────────────────>
0° … 359° (QDR)
Units
Tens
Hundreds
„Live“ bearing,
(QDR-value) L X X X [CR][LF]
││└───────────────>
│└─────────────────>
└───────────────────>
0° … 359° (QDR)
Units
Tens
Hundreds
Status S X X X [CR][LF]
││└───────────────>
││
│└─────────────────>
│
│
│
│
│
└───────────────────>
Error No.: 0 = Ok / 1…9 = Error No.
actual 0 = Off
Scan Mode 1 = Scan Mode: DOWN
2 = Scan Mode: M0..9
3 = Scan Mode: UP
4 = Scan Mode: ACT/M0
Status Info: 0 = Bearing signal off
1 = Bearing signal on
2 = RF TX deviation (no bearing)
3 = Test
4 = Ground transmitter suppression
5 = (Reserved for testing)
Frequency F X X X X X X [CR][LF]
│││││└─────────>
││││└───────────>
│││└─────────────>
││└───────────────>
│└─────────────────>
└───────────────────>
118,000 … 174,000 MHz
1)
kHz units
kHz tens
kHz hundreds
MHz units
MHz tens
MHz hundreds
Receive level P 0 X X [CR][LF]
│└───────────────>
└─────────────────>
000 … 099 %
Units
tens
Squelch Level Q 0 X X [CR][LF]
│└───────────────>
└─────────────────>
000 … 090 %
Units
Tens
Serial No. N X X X X X X [CR][LF]
│││││└─────────>
└─┴─┴─┴─┴───────────>
DF System Info
Licenced options: 0…8
Serial No. 00000…65534
Power On Time T X X X X X X [CR][LF] 000000 … 999999 [minutes] ( = max. 694 days)
1) Frequency output in the range 118.000 .. 136.975 MHz in accordance with ICAO Annex 10 Vol. V
Clause 4.1.2.4 Table 4-1.
See ICAO channel-frequency-table (air band)

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Timing and priority of cyclic data output
Message
„Average“ bearing approx. every 0,25 sec The first bearing value (after start of signal) will be transmitted
immediately. Without signal, no average value will be transmitted.
„Live“ bearing approx. every 0,1 sec With low priority. (in all available transmission breaks). Without signal, no live
bearing value will be transmitted.
Status approx. every 0,5 sec After start of signal, „S000[CR][LF]“ „S1000[CR][LF]“ will be transmitted
immediately.
Frequency approx. every 2 sec When frequency changes, the new frequency will be transmitted immediately
(also at active Scan Mode)
Receive level approx. every 0,5 sec
Squelch Level approx. every 2 sec
Serial No. approx. every 10 sec
Power On Time approx. every 60 sec
The following example shows the output of the average QDR bearing 315° as a sequence of ASCII characters
A 3 1 5 [CR][LF]
││││└──┴───> Final character (decimal: 13 and 10)
│└─┴─┴─────────> Content (bearing) (decimal: 51, 49, 53)
└───────────────> Header (decimal: 65)
Example of 5 sec data output (with start of signal, respectively begin of bearing)
Remark:
Data logging with Wireshark via TCPIP; Timestamp as additional info; final character is displayed here as „\r\n“ instead of [CR][LF]

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6.22Data Input
All received data are checked for correct syntax and plausibility referring to the actual unit setting. All received
data are also checked for compliance with the limiting values. The data input is monitored over a time-out of 100
ms, i.e. all ASCII characters of a message must be transmitted to the bearing unit within this time.
If errors are found, the received commands are not carried out. A correct data input momentarily sets the
direction finder to the required setting.
Message Header Content
Status S X [CR][LF]
└──────────────────> 0 = Clear average memory
1 = (not used)
4 = Ground transmitter suppression active
9 = Initiate System Reset
3 = Clearance for EEProm save functionality (1 sec active)
2 = Scan Mode: M0..9 start / continue
6 = Scan Mode: ACT/M0 start
7 = Scan Mode: UP start / continue
8 = Scan Mode: DOWN start / continue
5 = Scan Mode: STOP Stop (finish) active Scan Modes
Frequency F X X X X X X [CR][LF]
│││││└────────>
││││└──────────>
│││└────────────>
││└──────────────>
│└────────────────>
└──────────────────>
118,000 … 174,000 MHz
1
)
kHz units
kHz tens
kHz hundreds
MHz units
MHz tens
MHz hundreds
Squelch Level Q X X [CR][LF]
││
│└────────────────>
└──────────────────>
00 … 90 % (Standard inputfor digital squelch)
-1 (Receiver squelch potentiometer instead of digital squelch)
units
tens
MEM Recall R X [CR][LF]
└──────────────────>
0 … 9
Recall of one frequency memory from M0…9
MEM Store R X X X X X X X[CR][LF]
│││││││
││││││└──────>
││││││
││││││
│││││└────────>
││││└──────────>
│││└────────────>
││└──────────────>
│└────────────────>
└──────────────────>
Store of one valid frequency to the frequency memory M0…9
(used for channel scan mode M0..9)
0… 9( M0..9)
118,000 … 174,000 MHz 1) (valid frequency)
kHz units
kHz tens
kHz hundreds
MHz units
MHz tens
MHz hundreds
1) Frequencyinput is possible only within the valid range. Frequencysettings in the range 118.000 .. 136.975 MHz
have to be in accordance with ICAO Annex 10 Vol. V Clause 4.1.2.4 Table 4-1. Other inputs will be ignored
(also see ICAO channel frequency table next page).

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The following example shows the data sequence for the frequency command
(set new frequency 125,375 MHz)
F 1 2 5 3 7 5 [CR][LF]
│││││││└──┴───> final character
│└─┴─┴─┴─┴─┴─────────> content (valid frequency)
└─────────────────────> Header
ICAO channel-frequency-table (air band):
Frequency [MHz] Channel grid Channel / Frequency Input
FXXXXXXCRLF
118,0000 25 kHz 118000
118,0000 8,33 kHz 118005
118,0083 8,33 kHz 118010
118,0167 8,33 kHz 118015
118,0250 25 kHz 118025
118,0250 8,33 kHz 118030
118,0333 8,33 kHz 118035
118,0417 8,33 kHz 118040
118,0500 25 kHz 118050
118,0500 8,33 kHz 118055
118,0583 8,33 kHz 118060
118,0667 8,33 kHz 118065
118,0750 25 kHz 118075
118,0750 8,33 kHz 118080
118,0833 8,33 kHz 118085
118,0917 8,33 kHz 118090
118,1000 25 kHz 118100
118,1000 8,33 kHz 118105
118,1083 8,33 kHz 118110
136,9583 8,33 kHz 136960
136,9667 8,33 kHz 136965
136,9750 25 kHz 136975
Remark for frequency- and squelch input:
If a newlytuned frequency or squelch value are retained permanently in the system, even after a RT-1000 device
restart, it must be stored in the EEPROM device in addition. This is done by directly transmitting a previous "S3 [CR]
[LF]" commands.
Caution
Since the allowable write cycles to EEProms are limited, this option should be used only when necessary.