Sorry for the typo, i missed a couple of dots. It is the concept that is important more so than the numbers I used.
Element 1 ,(360nF and 7*.*5uH) Element 2 ,(1.5nF and 1.8mH) Element 3 ,(360nF and 7*.*5uH) On 22/11/2015 20:11, Paul Connolly wrote: > A spyverter would work (maximum power it could handle would be 200mW or > +23dBm and the maximum that the HackRF One can TX would be 15dBm - > https://github.com/mossmann/hackrf/wiki/HackRF-One#transmit-power ). A > spyverter would normally map DC-60MHz to 120MHz-180MHz but it can work > in reverse, just like a ham-it-up, 120MHz-180MHz to DC-60MHz. LF being > 30kHz to 300kHz is a bit low for the ham-it-up, it was designed to > convert signals in the MF and HF Bands (0.5MHz to 50MHz) to signals in > the VHF Band (125.5MHz to 175MHz). The ham-it-up will work, but with > more attenuation in the band that interests you ( > https://code.google.com/p/opendous/wiki/Upconverter ). > > You would still need a bandpass filter on the output before feeding it > into an antenna to avoid spewing the DC spike (and other birdies) into > the airwaves. So you would need to offset tune your signal away from the > central DC spike, making sure that the DC spike is well inside the > attenuation of the BPF. > > Lets say that you wanted to broadcast a AM signal at 100kHz with 9 kHz > bandwidth. > (ignoring any ppm offsets of the spyverter[or ham-it-up] and the hackrf > clocks for now, it is something that you will need to deal with) > So the signal that you want to TX would be at 120.100MHz(or 125.100MHz > on a ham-it-up) on the HackRF One. > And if the bandwidth was 8MHz on the HackRF and the centre frequency > could be tuned to say 122.100MHz so that the DC spike would be 2MHz away > from the signal that you want to TX. > > You sould make a BPF circuit that sits between the spyverter(or > ham-it-up) and the antenna - see below: > You can make a reasonable basic bandpass circuit with 3 inductors and 3 > capacitors. > (Random site found from a search for "bandpass filter calculator") > http://www.changpuak.ch/electronics/butterworth_bandpass.php > I gave it the following parameters: > Center Freq. [MHz] 0.1 (100kHz) > Bandwidth [MHz] 0.009 (9kHz) > Impedance [Ω] 50 > Order [1-19] 3 > > And it returned the following output: > --- start of result --- > Butterworth Bandpass Filter > www.changpuak.ch/electronics/butterworth_bandpass.php > Version : 10. Jan 2014 > ---------------------------------------------------- > Center Frequency : 0.1 MHz > System Impedance : 50 Ohm > Order of Filter : 3 > ---------------------------------------------------- > Element 1 , Orientation : shunt > C = 353677.651 pF, L = 7161.972 nH > Element 2 , Orientation : series > C = 1432.394 pF, L = 1768388.257 nH > Element 3 , Orientation : shunt > C = 353677.652 pF, L = 7161.972 nH > ---------------------------------------------------- > Appendix : Prototype G values > G[1] : 1 > G[2] : 2 > G[3] : 1 > --- end of result --- > > Approximate real component values can be substituted for the above, and > it should still work well enough, but you should really test the circuit > in a spice simulator to be sure of its frequency response. > Element 1 ,(360nF and 75uH) > Element 2 ,(1.5nF and 1.8mH) > Element 3 ,(360nF and 75uH) > > .11.2.2.33. > ........... >> ++-L-C-++> > .||.....||. > .LC.....LC. > .||.....||. > .GG.....GG. > ........... > .11.2.2.33. > > But if you are going to TX you should have a amateur radio license, in > most countries you would learn everything that you need to know in the > process of getting your license. > > On 22/11/2015 11:16, Dominic Spill wrote: >> On 18 November 2015 at 13:40, Frank Ch. Eigler <[email protected]> wrote: >>> I'm interested in receiving and low-power transmitting with the HackRF >>> at LF-range frequencies below, the 1MHz floor. What are the limiting >>> factors in the hardware or firmware that would impede transmitting a >>> 100kHz AM signal? >> The HackRF One transmit path passes a stream of complex bytes to two >> DACs, then combines these two analogue signals and finally mixes the >> signal up to the desired transmit frequency (in fact, HackRF shifts >> the signal twice, but that's not important for now). The hardware >> limitations will be filters at the baseband and at the mixing stage, >> which will filter out your LF signal. >> >> For this sort of operation I would normally recommend a ham-it-up >> device[1], but even they only go down to HF/MF. Perhaps other >> upconverters are available, but I haven't seen any to recommend. >> >>> As I understand it, receiving is probably OK via decimation in software. >> Have you tried this with HackRF One? I would assume that you will >> find the same issue with filters. >> >> Dominic >> >> [1] https://www.nooelec.com/store/ham-it-up.html >> _______________________________________________ >> HackRF-dev mailing list >> [email protected] >> https://pairlist9.pair.net/mailman/listinfo/hackrf-dev >
signature.asc
Description: OpenPGP digital signature
_______________________________________________ HackRF-dev mailing list [email protected] https://pairlist9.pair.net/mailman/listinfo/hackrf-dev
