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 Post subject: New to SDR? Start here
PostPosted: Sun Aug 16, 2015 7:41 pm 
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Joined: Thu Oct 04, 2007 1:58 pm
Posts: 3347
Location: Not in Alaska
Sounds like there are a few members here that are interested in getting in to SDR radios, so here's a few links to point you in the direction of where to get started. If you just want to run DSD you'll only need one. But to follow trunked calls of any kind, you'll likely need two.

The SDR unit

If you don't mind waiting 2 weeks, you can order from eBay. As of this writing the price is down to $7.96 per stick. The R820T is a little cheaper but the R820T2 chipset is vastly improved and well worth the additional 36¢. There are others that ship from the US but expect to pay a few dollars more.

If you have a little more cash to burn, you might try the sticks being sold by the rtl-sdr.com blog. These have two advantages: It has a SMA antenna connector (versus MCX for the above) and has a temperature-controlled oscillator:
The 28.8 MHz oscillator used in most RTL-SDRs is passive and not frequency accurate. This means that when you tune to a known frequency, it will likely be offset by a few kHz. Usually the PPM (parts per million) offset on a normal RTL-SDR is in the range of 30 – 150 PPM. Furthermore, as the dongle warms up, the frequency will drift up to ~20+ PPM until the temperature stabilizes.

These sell for $19.95 on Amazon and ship free with a $35+ order (or free 2 day if you have Prime). These ship from the US.


Antenna
The antenna that comes with the R820T2 is garbage. Even the rubber duck that came with your scanner is better. As with your scanner, the higher you can get your antenna the better, but since this is not always practical, a small portable antenna is in order.

I picked up something called a RT20 which appears to be a clone of the Maldol MH-209SMA. The RT20's performance is similar but not quite as good as the Madol, but I got a pair for $7.99 shipped so I'm happy. Combined with a SMA-f to MCX-m adapter it makes a great portable setup:

Image


Other
The RFI from your computer increases the noise floor on the SDR. If you don't already have a drawer full of them, ask Wilrobnson for one of his extra USB extension cables. Moving the SDR just a foot away from a PC makes a big difference.

Once you have all the equipment, follow Nick's tutorial for getting your SDR set up.


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