MF/HF radio test

 

Set Number

As you may wish to test several radios under the same MMSI, each radio can be given its own individual set number for recognition. Default number is 1. Press OK to confirm or press ↑ or ↓ to change to another number. Then, press OK and go to the test you wish to perform.

 

Receive DSC

In the Receive DSC test mode, the test box will receive the radio’s MMSI number and DSC data transmitted, and at the same time measure the frequency of the transmission. 

Connect the wire antenna supplied with the test box and use the setup below. The test box antenna should be able to “see” the transmitter’s antenna.

Recceive DSC (MF/HF radio test_image1)

Select Receive DSC and press OK. Then select whether the test box is going to receive the call on one of the TFC channels or MF/HF distress channels. Press OK and select frequency. Finally, press OK again and activate the transmitter.

The test box remains in receive mode until a DSC call is received. A press on the EXIT button can interrupt the mode, provided that the test box has not started to receive a call, in which case you have to wait for a few seconds. MMSI number, data and the MARK/SPACE frequencies are presented in the display and stored in memory, provided that the checksum is OK.

Test results are displayed line by line. Press ↑ or ↓ to toggle between the lines.

If the MARK/SPACE frequencies do not appear on the LCD display, the signal is most likely outside the limits 1770-1800 Hz / 1600-1630 Hz, or the signal was unstable during the header or that the header was too short (less than 11 bit). If data are shown as 255, it's because they were received in error.

Example of Printout from the Memory:

MF/HF # 1   Time/date: 08:25:18 / 21-11-2011
DSC DATA:  2187.5 kHz RX MMSI: 2195576240  Format 120 Cat.: 108
TX MMSI: 9999999990 Telecommand: 118 126 126 126 126 126 126 126
EOS: 117 ECC: 86  Status: OK
Mark: 2187414 Hz  Space: 2187584 Hz

The SPACE and the MARK frequencies are measured during the initial part of the DSC call. The measurements are done by means of a time measurement on an AF signal (1700 Hz +/- 85 Hz) derived from the MF/HF MARK/SPACE signal.

The time measurements for MARK and SPACE respectively are converted to frequency and the calculated values are added to an offset frequency for the actual MF/HF frequency. By adding the offset frequency to the measured/calculated frequencies the actual MF/HF MARK/SPACE frequencies are obtained.

The AF signal used for calculation of the MARK/SPACE frequencies must be within 1615 +/-15 Hz and 1785 +/-15 Hz respectively to be accepted.


Send DSC

In the Send DSC mode, the test box will transmit a DSC call for you to check on the DSC receiver accordingly. 

It is a requirement that the MMSI number registered in the test box is identical with the MMSI of the radio to be tested. Please check and change number, if required, using the Edit ship’s MMSI menu. See Page 12.

With selective calls, connect the relevant antenna supplied with the test box to RF OUT and use the setup below. The test box antenna should be able to “see” the transmitter’s antenna.

Send DSC (MF/HF radio test_image2)

If the transmission signal is not strong enough to enable the test, you may use the RF Amplifier (optional accessory) as shown here:

Send DSC with RF amplifier to enhance signal (MF.HF radio test_image3)

With distress calls, it is important to use a coax cable for the connection between the test box and the DSC receiver. This will prevent other ship stations to be alerted.

Use this setup with distress calls:

Send DSC_Distress calls (MF.HF radio test_image4)

To send a DSC call, select Send DSC and press OK. Then, select TFC or MF/HF respectively.

With TFC, select frequency and press OK. Select Normal or Reduced output power. Usually, normal power is recommended to send the call.

With MF/HF, select frequency and press OK. Select Dis to send a distress call or Sele to send a selective call. Select Normal or Reduced output power. Usually, normal power is recommended to send selective calls. Distress calls are always sent at reduced power.

Following the DSC call, the test box will display Received status. Press OK if the call was successfully received. Press Fail if the call was not well received. The answer will be stored in the test box memory for your test report. 

Please note: Some DSC receivers have a built-in delay of 1-2 minutes before they acknowledge distress calls. 

 

The TFC selective call transmits the following information: 

120,120                                Format specifier - individual call.
21,95,57,62,40                     Address - 2195576240
100                                       Category - routine
99,99,99,99,90                     Self identification = Testbox “MMSI No”.
109                                       First telecommand
126                                       Second telecommand
126 126 126 126 126 126    Frequency or channel 126 transmitted six times
117                                       Ack. RQ  End of sequence
69                                         Modulus-2 checksum

 

The MF/HF selective call transmits the following information: 

120,120                               Format specifier - individual call.
21,95,57,62,40                    Address - 2195576240
108                                      Category - safety
99,99,99,99,90                    Self identification = Testbox “MMSI No”.
118                                      First telecommand 
126                                      Second telecommand
126 126 126 126 126 126   Frequency or channel 126 transmitted six times
117                                      Ack. RQ  End of sequence
86                                        Modulus-2 checksum

 

The MF/HF distress call transmits the following information:

112,112                       Format specifier - Distress call
99,99,99,99,90            Address - Testbox “MMSI No”.
107                              Category - Undesignated distress
99,99,99,99,99            Co-ordinates - 99 99 99 99 99 at test.
88,88                           Time - 88 88 at test.
109                              First telecommand
127                              EOS - End of sequence
48                                Modulus-2 checksum

 

Send custom DSC

The Send custom DSC mode enables the test box to send a custom-made DSC call composed in advance on a PC. For the purpose of composing, a free PC software TEST BOX MANAGER can be downloaded from Danphone’s website. See page 48.

Once downloaded, connect your PC to the test box via the USB cable supplied. Follow the instructions of how to compose a new custom-made DSC call and to transfer it to the test box accordingly.

To make the test box transmit the custom-made call, select Send custom DSC on the test box and press OK. Then, select TFC or MF/HF respectively.

With TFC, select frequency and press OK. Select Normal or Reduced output power. Usually, Normal is recommended to send the call.

With MF/HF, select frequency and press OK. Select Normal or Reduced output power. Usually, Normal is recommended to send the call.

Following the DSC call, the test box will display Received status. Press OK if the call was successfully received. Press Fail if the call was not well received. The answer will be stored in the test box memory for your test report.  

If there is no custom made call in the test box, the display will say No custom data.

 

Signal level

This mode can be used to check the signal strength level of the received signal at 2187.5 kHz.

The level figure is used to indicate if the signal strength is sufficient to ensure proper radio communication between the test box and the radio during the following tests.

Signal level (MF.HF radio test_image 5)

For an indication of the actual signal strength level, select Signal level and press OK. Following this, the frequency will appear in the display. Then, press OK and start transmission from the radio. The level figure appears in the test box display. A figure of 70 or higher is advisable.

 

Test Sensitivity

This test mode enables you to check the sensitivity of a MF/HF receiver.

Use this setup:

Test sensitivity (MF.HF radio test_image6)

1) Set the receiver to 21,000 kHz.
2) Select Test Sensitivity on the test box and press OK.
3) Select High to send a test signal at -90 dBm, or Low to send the signal at -110 dBm. With this, the test box transmits 21,001 kHz modulated with 1 kHz at the requested level.
4) Check that a 1 kHz tone can be heard in the radio’s speaker.

 

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