The correct terminology for a Flex Radio. "Open Source software defined radio."
John P. Basilotto W5GI Chief Operating Officer Marketing and Sales Office 512 535-5266 FAX 512 233-5143 www.flex-radio.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jim Lux Sent: Tuesday, November 20, 2007 10:10 AM To: Dudley Hurry Cc: FlexRadio@flex-radio.biz Subject: Re: [Flexradio] Power SDR w/other radios Quoting Dudley Hurry <[EMAIL PROTECTED]>, on Mon 19 Nov 2007 08:47:05 PM PST: > Nope.. Nearly all other radios are Software Controlled Radios, the > 5K is a Software Defined Radio. The Softrock can be used with > PowerSDR console also. > > > At 09:54 PM 11/19/2007, Ken wrote: > >> I have been using the new Flex-5000 and loving it! >> However, I also have a TS2000 and an IC7000. Can the Power SDR be used >> with either one of these radios? >> The IC7000 *is* a software defined radio, just the software happens to be a prom that is not user changeable. The main difference between software based radios like the IC7000 and the Flex radios is that in the latter, most of the signal processing is done in software that is running on a general purpose commodity PC, as opposed to a mask programmed DSP. PowerSDR provides three basic functions: User interface, Hardware control, and Signal processing. Something like Ham Radio Deluxe hooked up to my IC7000 provides just the first, with the IC7000 responsible for managing the RF hardware and providing the signal processing (a mix of analog and digital). Interestingly, the SDR1000 and Flex5000 differ a bit in the middle function, hardware control. For the SDR1000, PowerSDR has to do all the work of controlling the DDS, for example, calculating the phase increments, loading it out in bytes to the AD9854, etc. In the F5K, PowerSDR just sends a "set the frequency" message to the box, which then takes care of the gory details of hardware control. Actually, terms like SDR get bandied about quite a bit with different people meaning different things. Here's some background. <flame suit on.. this gets controversial> Software controlled: Something where the hardware design defines how the radio works, but has "switches and knobs" controlled by software. My 20 year old FT757 is software controlled: there's a microcontroller inside that sends commands to the CMOS switches, relays, and synthesizers in response to things like button presses and turning the tuning knob. Remote controlled: There's an external interface that lets you send commands and get telemetry back (My 20 year old FT757 responds to commands on a TTL serial port, and returns the AGC voltage.. the IC7000 uses the CI-V protocol, etc.) Digital radio: A radio where signal processing is done by digitizing the signal and doing stuff with the digitized samples. Software Defined Radio: A radio where some of the *signal processing* is done in software (e.g. modulation, demodulation, filtering). The key aspect is that the overall function of the radio can be changed without changing the hardware design. This would exclude some "digital radios" where the signal processing is done digitally, but by fixed logic that is not programmable (e.g. designs from the 70s and 80s using Multiplier Accumulator chips and NCOs). The term "software reconfigurable" is often used to distinguish from radios which use DSP (software) to do the signal processing, but where it's in a mask ROM or similar non-changeable form. That is, the radio's behavior and function can be changed fairly easily, without replacing a physical component. Here's where the arguing starts... if it's a "soft"ware defined radio, is a radio that does processing with a DSP and the software in PROM a SDR or "firm"ware defined radio? What about a radio where the signal processing is done in a FPGA, either one-time-programmable, or reprogrammable, and, if the latter, does it matter whether the FPGA configuration data is stored in PROM vs EEPROM/flash vs RAM/diskdrive. There's also a distinction made by whether the signal processing is done by a general purpose processor (as in the Flex-Radio products) or by a specialized processor (DSP10 or USRP). All of these are "soft" in the sense that it's pretty easy to change the function of the radio, without changing the hardware. There's all sorts of gradations, too. Some folks think "software radio" should really only apply to "antenna/LNA connected to A/D", with all tuning and conversion done in the digital domain by programmable logic and processors. (Most GPS receivers fit here, by the way.) Others allow some frequency conversion and/or bandlimiting ahead of the A/D (the Flex-radio products fit here, especially if you run a transverter), but do most of the tuning and filtering in the digital domain. Yet others have software radios with fairly conventional superheterodyne design to baseband or an IF, then digitize that and use software/firmware from there back. The IF is often chosen to have some relationship with the A/D sampling rate (e.g. an odd multiple of sampling rate/4). Most spacecraft radios/transponders being designed these days use this architecture(e.g. an IF of 130 MHz sampled at 40 MS/s), as do radios like the IC7000 (which has a last IF in the 10-20kHz range for narrow band signals). The choice of frequency plan is driven (mostly) by selectivity and signal bandwidth. The IC7000 has to deal with lots of narrow band signals in a dense environment. A radio at Mars doesn't have these problems, but does need fairly wide bandwidth to accommodate high rate signals and doppler uncertainty. The key is really that "software reconfigurability"... you can implement a new modulation format without changing the hardware. Not just changing the parameters of an existing format (e.g. FM deviation or filter bandwidth), but whole new modulations (e.g. OFDM instead of BPSK, FM instead of AM or SSB). Hams have been doing this for a number of years already with "sound card modems" for things like PSK31, Olivia, etc., using a standard SSB transceiver as a tunable RF front end transverter to audio frequencies. It was a natural outgrowth from dedicated modems when PCs got powerful enough to do the processing. Is my FT757 with MultiPSK on a laptop a "software defined radio"? I can load up Stream instead, and have a different implementation of the modem and user interface. In the (pro) SDR world, by the way, these are called "waveforms" which are instantiated on a "platform". The term waveform is a bit confusing at first; consider a radio as a transducer/translator between information on one side (voice, data, contact closures on a paddle) and some RF signal. The waveform defines everything about that transformation, not just the actual voltage vs time of the RF. For instance, it can encompass all the protocol details in a digital data protocol. Conventional 2m APRS for instance, is a waveform, composed of a modulation spec (AFSK at 1200bps), a protocol (AX.25), and a protocol on top of that (the APRS message formats), and some defined behaviors for relaying, etc. In theory, I can implement the APRS waveform on ANY suitable SDR platform (assuming it can tune the frequencies and has sufficient computational crunch and the right interfaces). And, any APRS waveform implementation should be able to talk to any other APRS waveform implementation over the air. These days, there's not much claim for portability of the actual waveform implementations, at least in the ham world (that is, I can't take APRS implemented for platform A and just drop it into platform B and have it work), although there is a lot of work towards just that end in the Department of Defense (JTRS) and in the commercial world (OMGs SCA). And, certainly, pieces of ham waveform implementations are portable (e.g. dttsp implements FM and AM modulators and demodulators, and is fairly platform independent. There are digital mode programs that run on lots of different hardware brands with a variety of OSes. etc.) In the case of PowerSDR, it's compatible with several hardware platforms (SDR1000, Flex5000, SoftRock), but RF architecture-wise, those are all quite similar. Adding support for a very different RF hardware platform would require substantial software changes to PowerSDR (the changes to dttsp would be fairly small, if any) jim, w6rmk _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/ _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
