Hi!
I've borrowed a Funcube Dongle Pro and tried to use it with osmocom-tetra. I've manually tuned it to a tetra carrier using the Qt-GUI, and it I can see the carrier very clearly in the spectrum/fft. However, I'm getting many more bit errors than with a USRP2+WBX board. Also, I have the feeling that the WBX has a much higher sensitivity, even with the FCDP input LNA at 30dB maxed out.
Can anyone confirm these findings?
I'll do some more investigation and report back here.
Regards, Harald
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Hi Harald,
I have no Funcube, but from the design of it I would rather assume, that it is a matter of strong signal immunity. The WBX has a lot of built in analog filters whereas the Funcube has none. If several other carriers are in the vicinity (within several MHz of the targeted signal), all these add to noise in the channel.
You might try a filter between antenna and Funcube or try to use an antenna that is only sensitive in a small part of the Tetra band. Do not use one of these DVB-T mini antennas that come with the USB sticks. These are optimized for covering the whole TV band. This includes Tetra but also everyting else :/
Just my .02 - and speculation as well...
Best regards, Christian
On 25.05.2011 08:57, Harald Welte wrote:
Hi!
I've borrowed a Funcube Dongle Pro and tried to use it with osmocom-tetra. I've manually tuned it to a tetra carrier using the Qt-GUI, and it I can see the carrier very clearly in the spectrum/fft. However, I'm getting many more bit errors than with a USRP2+WBX board. Also, I have the feeling that the WBX has a much higher sensitivity, even with the FCDP input LNA at 30dB maxed out.
Can anyone confirm these findings?
I'll do some more investigation and report back here.
Regards, Harald
- -- - --------------------------------------------------- | maintech # Dipl. Inf (FH) Christian Daniel | | GmbH ### Otto-Hahn-Str. 15 · D-97204 Höchberg | - --------------------------------------------------- | AG Würzburg, HRB 8790 Tax-ID DE242279645 | - --------------------------------------------------- | http://www.maintech.de cd@maintech.de | - ---------------------------------------------------
You might try a filter between antenna and Funcube or try to use an antenna that is only sensitive in a small part of the Tetra band. Do not use one of these DVB-T mini antennas that come with the USB sticks. These are optimized for covering the whole TV band. This includes Tetra but also everyting else :/
On that subject, can anybody recommend a good portable antenna for use with the FCDP?
At home, I can pick out some (presumably) TETRA signals (in NRW, DE) by hooking up to a DVB-T booster antenna I have and scanning around 420MHz.
As mentioned, portable laptop antennae like those for WLAN and DVB aren't ideal. So I'd be interested in finding something to use while out-and-about with the FCDP, which could be good for picking up the most common TETRA bands.
Thanks, Chris
Hi Christopher,
On Fri, Jun 03, 2011 at 10:39:37PM +0200, Christopher Orr wrote:
On that subject, can anybody recommend a good portable antenna for use with the FCDP?
At home, I can pick out some (presumably) TETRA signals (in NRW, DE) by hooking up to a DVB-T booster antenna I have and scanning around 420MHz.
As mentioned, portable laptop antennae like those for WLAN and DVB aren't ideal. So I'd be interested in finding something to use while out-and-about with the FCDP, which could be good for picking up the most common TETRA bands.
I'm using a combination of digikey numbers ANT-418-CW-HWR-RPS-ND and ACX12470ND with my FCDP.
The other thing that I've ordered (but not yet received) is a car antenna with magnetic foot: Procom MU 4-MM/CEL4
(the MM indicates the magnetic foot, you can get any other mounting option that Procom supports)
This is a 4dB gain antenna for the 414 - 430 MHz range.
They have other antennas for different ranges like 380-400 MHz (CEL5): http://www.procom.dk/eng/Page_menu/Products/Mobile_Antennas/225_-_470_MHz/Ge...
For the Procom antennas you typically need a FME cable plus a FME-SMA adapter.
Regards, Harald
Hi,
from my observations the dongle is about 10 dB worse in terms of dynamic range than the WBX (measured the same carrier on the same (wideband) antenna, WBX gain 0, FCDP all gains at their lowest values). Raising of any of the FCDP's gains leads to signal shape degradation with my setup.
Demodulation seem to work fine here with an SNR of around 40 dB.
Best regards,
Dimitri
-
Christian Daniel -- maintech GmbH -
Christopher Orr -
Dimitri Stolnikov -
Harald Welte