There is a necessity for annual or issue inspections of ELTs after receiving of type approval. The problem is a complexity of the basic beacon signal parameters, which could not be measured with the simplified handheld testers. The most complicated for measuring and the most important for reliable communication to satellite and accurate position calculation are the frequency stability and phase modulation parameters. As a rule they require specially designed equipment in addition to standard measurement instruments (spectrum analyzer, frequency counter, etc.) which are not usually available on a ship board.
 The BT611 is easy-to-use unique COSPAS - SARSAT ELT tester designed for high accuracy and resolution measurements of the full set of ELT signal parameters to check its compliance with the ones, specified in C/S doc. T.001, T.007.
It allows to check visually frequency and phase behavior inside the burst during CW preamble and when it is modulated, statistical frequency stability parameters and, as a useful option to COSPAS/SARSAT requirements - rms frequency variations between the bursts. All specified burst and modulation time intervals are displayed.
The Tester provides high stability results when used by laboratories, manufaturers or during field beacon tests.
BT611 ELT Tester allows to perform not only control tests, but comparing evaluation of different EPIRBs parameters, too. When using BT611 you only have to connect it to PC. All basic parameters including mentioned ones will be accurately tested.
The instrument integrates two independent amplitude and frequency measurement channels for 406.025 MHz and 121.5 MHz beacon transmitters. Any IBM-compatible computer could be connected to the instrument RS-232 port. Measurement functions and displayed results formats (graphics or tables) are selected from the computer key-board and soft-key menus.
| The main accuracy features |
| Parameters to be measured |
C/S required accuracy |
BT611 accuracy |
| 406 MHz channel |
| Frequency stability |
1*10-10 |
5*10-12 |
| Nominal frequency |
+-100Hz |
+-50Hz |
| Inside burst Frequency shift |
- |
0.1Hz |
| Modulation index |
0.04 rad |
0.006 rad |
| Modulation rise and Fall times |
+25 ms |
+10 ms |
| Bit rate |
0.15% |
0.05% |
| Power (when directly connected to the beacon) |
10% |
5% |
| 121,5 MHz channel |
| Carrier frequency |
- |
+-10 Hz |
| Max. and min. Sweep Audio frequency |
- |
< 10% |
| Modulation index |
- |
+-20% |
| Peak power |
- |
+-10% |
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Operating environment:
- operating temperature 10...45°C;
- relative humidity up to 70% at 45°C.
Storage conditions:
- temperature -40...70°C;
- humidity up to 90% at 60°C (non condensing).
Weight:
- net - 2 kg;
- gross - 2.2 kg.
Dimensions:
- measuring device - 254x260x65 mm
- antenna (when assembled):
- height - 25 mm
- bottom diameter - 260 mm
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