Ubbe
Member
It works like any other SDR dongle. If you reduce gain it will work better. But this chip in the SDS scanners have automatic gain that adapt to the RF situation, it is designed for constant levels of all signals from a tv transmitter or satellite dish. It is not design to handle transmitters that key on and off at different frequencies and with different signal strenghts. Unfourtunatly the automatic gain cannot be disabled in the chip.
The receiver chip had too bad sensitivity to begin with for scanner use so Uniden added a pre-amp with programmable gain levels. This gives it good sensitivity but the intermod and bleed over then increase. There was a long time where different gain levels for different frequency bands where tested in different firmwares. Finally the gain levels where set that suited most people.
That automatic gain function are monitoring the RF signal level over a wide frequency range, you can see my tests in that Global auto filter thread. A strong transmitter way off in frequency will make the gain to be reduced and all frequencies in that band will loose sensitivity. It's a hardware design and cannot be fixed by FW. The intermod and bleed over might be fixed by FW but then only by reducing the total gain in the scanner that will make it have the worse sensitivity of any modern scanner produced. It will probably equal to always have the attenuator enabled.
Unidens representative said to only buy a SDS scanner to solve the simulcast issue, as it has so many other issues when used as a conventional scanner.
/Ubbe
