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Re: Thoughts on a Ham Bus
Jack Purdum
Jerry: All thoughtful points, many of which I didn't even consider. I remember trouble shooting the S100 bus using "extender cards". It made it possible, but it wasn't ideal. Any "rank mount" has to keep that in mind. It seems to me that the bus bottleneck is most severe on the transmit side, whereas the receive side might lend itself to more standardization. Personally and for obvious reasons, I want to mess around with SDR rigs. I don't know enough to write one...yet, but I would like to learn about them. IT just makes sense to push things out of hardware and into software where possible. That said, I don't want to be tethered to a PC or laptop in the process. I want the computing horsepower to be part of the rig. As I said, I don't have the talent to carry this forward, but segmenting the xmit/rec elements might help define a bus that could work. Jack, W8TEE
On Thursday, June 21, 2018, 11:41:33 AM EDT, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
On computers, a standard bus makes sense, they are just shipping around data and don't care exactly how that happens so long as it is fast and error free.? And maybe some source of power. Requirements of a "standard bus" for a radio are going to be all over the map, depending on? what the radio does, frequencies of interest, how the boards are split up, power levels, ... A radio with a motherboard into which various modules get plugged into is not a bad idea. The PCIe connectors themselves work well, are cheap, mate with just a properly routed PC board.? But that motherboard will be an ad-hoc collection of signals, nothing like implementing a PCIe bus for a PC.? Unless, possibly, it's an SDR.?? Modules are good though.? I like the thought of a bunch of boards that plug together into a stack on 0.1" headers, rather like Arduino shields.? And perhaps slides into one of the many extruded? aluminum boxes with rails.? ? On the uBitx, might be two boards split between the first mixer and the 30mhz LPF, so the SSB exciter could be used with various versions of the PA, with its various filters and power? levels and frequencies.? A third board could optionally be stacked on top of the PA for an automatic antenna tuner for those keen to have something special to talk about on the air. Different PA boards for those wanting cheap and functional vs those insisting on "real" RF parts. Perhaps a different PA board with rx preamp and SWR meter for 1296 mhz.?? But for all those cases, the connection between boards could be kept quite simple.? Just one RF wire plus power plus an i2c/spi bus.? ?I would not want the burden of some $100 motherboard that attempts to "do everything" (whatever that is) when I join those boards. Of course, you may someday want another optional board in the stack on the other side of the uBitx exciter to implement digital modes using an RPi.? ?And a 7" display stacked on top of that. Those interconnections might be quite different than that between the exciter and the PA. But easily handled by a different header from exciter to the digital board. Stacks of boards can be very tough to tinker with.? I prefer to keep connections mostly along one edge of the board so a short flexible cable (or U-shaped assembly of two connectors and a small board) can be slipped in there and the boards folded out for easy debug.? Ideally, use the far side of the board for a connection to the next board up so you can fold out all three flat on the desk.? Of course, I've never built a radio like that.?? And will likely have a totally different idea of how best to go about it once I do. But a generic ham-bus that satisfies everybody seems unlikely. Jerry, KE7ER? ? On Thu, Jun 21, 2018 at 07:40 am, <tituskz1g@...> wrote:
I've worked with computer buses since the early '70s.? Most buses get standardized about the time they become obsolete.? Trying to set a standard simply forces people to look elsewhere for something better, which they also want to standardize.? And so it goes... |
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