Hello people, I'm aiming to transmitt in some amateur radio bands, especially the 40m band. The bands that LFRX and LFTX can cover are (considering the 30MHz lowpass filter): 1.8, 3.5, 5, 7, 10.1, 14, 21, 24.89, 28 MHz I know gnuradio can do SSB and CW modulation :) I'd like to know the output power I can get from a usrp 1, and if someone has any experience with this kind of experiment, like what amplifiers to use, what filters, and things like that. Thanks, Rafael D.
on 2008-10-27 03:09
on 2008-10-27 19:50
On Sun, Oct 26, 2008 at 9:08 PM, rafael2k <firstname.lastname@example.org> wrote: > I'd like to know the output power I can get from a usrp 1, and if someone has > any experience with this kind of experiment, like what amplifiers to use, > what filters, and things like that. The maximum USRP1 output using the LFTX board is approximately 2V P-P into 50 ohms, or about 10 milliwatts rms. Depending on your waveform peak to average ratio, your rms power will be less. On TX, to get to say, a max of 5W for QRP operation, you'd need a PA with at least 27 dB of gain. For operation with SSB, this would have to be a linear amplifier. For CW only, you could use a non-linear PA which would be easier to design. The LFRX board has no gain, and essentially just provides anti-aliasing filtering and impedance matching between the input at 50 ohms and the analog-to-digital converter input circuitry. You can think of it as having roughly a 55dB noise figure, so you'd need at least that much external low-noise amplification to get any sort of useful weak signal reception. (The 55dB figure was from an empirical measurement with a signal generator; YMMV.) Since the ADC is digitizing the entire 0-30 MHz spectrum, it would be essential to have a band filter ahead of the amplification, in order to avoid strong out-of-band signals limiting the amount of gain you could use. In addition, you'd want some sort of analog AGC. Anyway, it's obvious the LFRX and LFTX were designed as baseband interface cards, not as an HF receiver or transceiver. Still let us know what you come up with. It's certainly possible, given the open design of the USRP1/USRP2, that you or someone else could design customer daughterboards that incorporate some or all of the above. -Johnathan (AE6HO)
on 2008-10-28 02:40
Thanks Johnathan, I'll try to get such amplifier and probably a passband filter. I send the schematics to the list If I get something working. There are others SDR radios out there that were made for amateurs, like Flex5000, softrock and others, but they all use a stereo sound cable connected to the PC soundcard as interface (at most 96kHZ and 20kHz bandwidth), ..., ursp is much more powerfull. bye, Rafael D. Em Monday 27 October 2008, Johnathan C. escreveu:
on 2008-10-28 03:12
On Mon, Oct 27, 2008 at 8:36 PM, rafael2k <email@example.com> wrote: > There are others SDR radios out there that were made for amateurs, like > Flex5000, softrock and others, but they all use a stereo sound cable > connected to the PC soundcard as interface (at most 96kHZ and 20kHz > bandwidth), ..., ursp is much more powerfull. There are exceptions to your "they all use a stereo sound cable" rule. One that you might want to look at is here http://hpsdr.org/ There are several sub projects within HPSDR. Look at both of these: http://hpsdr.org/mercury.html http://hpsdr.org/penelope.html -- ===== Chris Albertson Redondo Beach, California
on 2008-10-28 17:11
thats true Chris, Thanks for the information. but none runs gnuradio, usually PowerSDR is used. bye, rafael diniz Em Monday 27 October 2008, Chris Albertson escreveu:
on 2008-10-30 00:24
And do not forget the new QS1 http://www.philcovington.com/QuickSilver/
on 2008-10-30 00:35
On Wed, Oct 29, 2008 at 6:23 PM, Robert T. <firstname.lastname@example.org> wrote: > And do not forget the new QS1 > > http://www.philcovington.com/QuickSilver/ I guess it's helpful to see some validation of USRP2 pricing. :) (It looks like a RX only USRP2 plus USB2.0 bottleneck, minus external refclock) An RX only device doesn't meet Rafael's interest though: Anyone working on a GNU Radio driver for this thing?
on 2008-10-30 00:41
The transmitter is being designed now... From the QS1R Yahoo group: "The SRL QS1R features expandability with an I2C and SPI/Microwire expansion bus. Also planned is a PCI interface version of the QS1R with accompanying DAC/transmitter board as well as various VHF/UHF/Microwave add-on boards."
on 2008-10-30 03:18
That one is nice. but the price is not that good, and the software runs on Windows... (of course we could write the driver to gnuradio). btw, back to our ursp/gnuradio, a friend that works w/ RF will try to design a board that conects to the LFTX w/ the stuff needed to transmit SSB and so on. If I get something, I email to the list. I already transmitted from gnuradio to a 2m amateur radio without any add-on, just the standard BasicTX. :) bye, rafael diniz Em Wednesday 29 October 2008, Robert T. escreveu:
on 2008-10-30 03:46
Nice gadget, but prices are insane. cheerio Berndt
on 2008-10-31 04:49
The code is open source and being ported to Linux. Integration with GNU Radio is being planned.
on 2008-10-31 05:33
Hi Tiller, Wow, very nice to hear that!!! Is there any code of this port already available? bye, rafael diniz Em Friday 31 October 2008, Robert T. escreveu: