#Sdr sharp for mac manual
The design I am basing the upconverter off of is that by W9RAN(featured in January 2013 QST and available for $40 in kit… but I need to customize with compartmentalized shielding and stuff, and it includes manual bypass of the upconverter(separate HF, VHF/UHF antenna inputs). I occasionally hear it on my telephone and speakers(without being hooked up… it’s spooky as hell walking into a room and hearing voices on a disconnected speaker!) I’m a little worried about the low HF… I’m 1/4 mile from an AM broadcast station. And it’s an UPconverter bringing the HF(DC-60Mhz) signals up to the range of the receiver(~60-2200MHz), while keeping those signals out of the FM broadcast band(88-108MHz)… so that the HF will be tunable by the receiver software(HDSDR) with a -125MHz offset (125-180MHz). In other words, yes, it’s the POS dongle I have :) As far as SMD goes, my hands aren’t the steadiest anymore… In this case, I believe the term is “image noise”, in this case. Anything not a real signal is noise, including that caused by the hardware itself. It’s worse in certain bands(like 2m 144-148MHz) I call the spikes noise because that’s what they are. It turns out the oscillator for this thing is 28.8kHz. Garbz: I think they are indeed specifically from poorly filtered/shielded oscillator. Kendall: Thanx! I completely forgot eBay! I would much rather have a DIP-4 package. Soldering a bacon-bit isn’t exactly something I look forward to. I’ve never done SMD and I’m not sure if I’m really equipped for it. I’m having a bitch of a time sourcing a 125MHz oscillator that’s not SMD, though. Plus, if the dongle is in the box, I can provide it with a better ground than going though the guts of the computer through the USB. I’m gonna throw in a 1:1 balun/isolator on the inputs, just for S&G. I’m planning on building a 125MHz NE/SA602-based upconverter for tuning HF and I’m thinking of putting the dongle in the box so I can isolate it from and RF and provide some forced-air cooling. I personally use HDSDR but SDR# is good, too… just not as much eye-candy. That vastly improved things as far the noise floor, but the spikes are still there(not to mention the huge LO spike in the middle).
I had an old scanner mast dipole I broke out and ran RG-6 to it with a PAL(Bellman-Hughes or whatever) to F adapter. And the stock antenna does suck… I don’t even think the “coax” is shielded. Spikes every 28kHz or so across the whole 2MHz slice… and the thing gets hot after a while. I’m using an RTL2832/E4000-based DVB-T dongle from Europe, and the IF noise(presumably) is just horrible. We do this where I work, we bridge a local legacy Motorola Smartnet system to a Motorola TETRA system and to a MotoTRBO system 15km down the road owned and operated by another company with whom we have to remain in constant communication. Also just because systems are not the same doesn’t mean you can’t bridge between them. There’s no doubt the entire state will move to the same system eventually (in this case P25) however the move will take time.
In Australia the states have taken a dim view of going to the extent to encrypt communications and then route it through infrastructure owned by a private company, so instead they setup their own. In Great Britain the Airwave project was created in a public-private partnership which has the overseeing entity Airwave Solutions making money hand over fist every time anyone in the country hits the PTT button. Also TETRA is really the defacto standard for modern 2-way communication, it’s just a question of who will pay for the infrastructure.
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