Making the Connection to the PC

In the case of connecting a receiver to the PC sound card, a clean connection is a must. Many hams use dedicated terminal units or even sound card interfaces; and some (like the PK-232SC) have adjustable filters that can help reduce interference from adjacent stations. While that works well in the amateur service, those filters can actually cause an otherwise readable signal to be unintelligible. This is because those filters are often tuned to mark / space tone pairs common in the amateur radio service – but those tone pairs may not work for many non-ham digital modes. If you use such a device, first investigate whether these filters can be turned off or otherwise disabled.

The best way to go is to connect to the sound card via a cable or an interface that has no such filtering. This article from our wiki describes some Windows-related pitfalls and solutions. It's strongly encouraged to make the connection with shielded audio cable to restrict the possibility of stray noise pickup. However, you will need to experiment with the sound card settings on the PC to see which works for you. There's no way to present a guide for each and every instance, as there is wide variation in models and quality, depending on the sound card installed on the PC.

Connecting a PC to your SDR depends on what the SDR has for outputs, and sometimes the software you are trying to use.

• Some SDRs have an output that can be used to feed your sound card (i.e. Cross Country SDR 4 Plus).
• Some software will require the use of some Dynamic Link Libraries (DLLs) that must be installed (MultiPSK).
• With some you need to use software like Virtual Audio Cable (VAC) to route the audio from the SDR to the PC. See the HF Appendix for the link.
• Some packages can directly interface with certain SDRs without additional interfaces. You can see the list of such decoding software at the SDRs and Digital Decoding article.
• Some SDRs and one desktop receiver (the Alinco R8T) have an IQ output that may also be used. In the hobby level market, only Sorcerer is known to be able to accept an IQ output for data analysis and decoding.

Up to this point, we've discussed audio connections - but what about software that include receiver control (and possibly logging) for desktop receivers? You will need a USB-serial connection, in most cases, in addition to the audio connection (RS232 devices are not designed to carry audio signals). This varies greatly by manufacturer, and it's unfortunately beyond the scope of this document to cover them all. However, you're not without resources; most every receiver has at least one associated Yahoo group - these are some of the best places to find information on the various requirements each receiver will present to the user. We have a list of such mailing list (though not necessarily complete) in the HF Receiver Mailing Lists article. For mailing lists devoted to certain SDRs, see the SDRs with HF Coverage article.

You may also want to check out the Connecting scanners via USB article, as much of what is written there is also applicable (with a little work) to desktop receivers. Start from section 4 - Generic USB to RS232 Serial Converters. If you are using Win 8.x, see section 5.3 - Windows 8 Issues and Solutions.

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