[minima] Re: BSS-1 Transceiver Project
- From: farhanbox@xxxxxxxxx <farhanbox@xxxxxxxxx>
- To: joe@xxxxxxxxxx <joe@xxxxxxxxxx>, minima@xxxxxxxxxxxxx <minima@xxxxxxxxxxxxx>
- Date: Sun, 11 Jan 2015 18:10:56 -0800 (PST)
i did make this kind of a thing a few years ago. here is the video
:Sweeperino's working: http://youtu.be/qRNOp1F81i8
for an evening or two's work, it worka very well. however, you must be careful
to understand a few things:1. the.ad8307 is a microwave device. it has more
than 1 ghz product bandwidth. thus, when without filtering, it tends to pick up
a lot of noise generated by the dut, limiting the lower limit of signal pick
up. in my case,.it hovered around -70dbm.2. the dds has spurs, in addition to
spurs, getting harmonics free signal is impossible. as a result you will see
responses to bandpass.filters where none ought to be. an LC bpf will display
significant responses at all batmonics.3. in order to beat the spurs issue, i
used an Si570. the vhf output is hetrodyned to hf. this was reltively cleaner
but the iip3 and the iip2 products are still there.the sweeperino is quite
useful, still. i regularly use it to measure crystal filters, LC filters,
gains, etc. but i have to mentally discount harmonics. in the end, nothing
beats a specan. i.just finished brewing one. i will post the details soon. it
has 1hz resolution, 80db imdr free range, works to 70 mhz in 1khz and 300 khz
ranges. here is an early version https://m.youtube.com/watch?v=dkQTSFjqY5k
- f------ Original message------From: Joe RocciDate: Mon, 12 Jan 2015 04:25To:
minima@xxxxxxxxxxxxx;Subject:[minima] Re: BSS-1 Transceiver Project
See below:
But USB interfaces, porting graphing software and libraries to an available
host machine and host OS, substituting in some other microprocessor (I might go
with a TI Tiva, so I can play with digital modes), that can get complex.
No one can be all things to all people, so you have to choose your battles
carefully. For me, I long ago accepted that it's an Arduino world (even though
I'm a PIC guy) and that Windows isn't going to budge from its dominant market
share for a long while. Consequently, I'll design around an Arduino Nano with
the PC application written in Visual Basic. That's my poison....you can poison
yourself any way you wish.
Building something that works well with a particular parts list and host
computer would be a notable achievement. But I would at least give some
thought to making it easily understandable, adaptable to other parts, and
hackable. Note all the variations on the minima thus far.
It will be open-source. I'll post the Eagle design files as they become
solidified and will also submit them to a couple low-cost PCB houses so others
can order boards directly from the source. All my parts lists will have DigiKey
part numbers. That's about as far as I can go without violating my maxim about
being all things to all people.
Perhaps I'm a Luddite, but I prefer a UART interface in my projects. If it
needs to talk to a USB port on the host then that can happen through something
like an FTDI cable. The USB spec is currently around 42 MBytes, a basic UART
port can be fully described in one Kbyte of text. Most of the complexity in
USB gets hidden, a bad thing when it doesn't work. I can figure out what's
going on with a UART by poking it with a scope, not so with USB. A UART
interface can be implemented through generic IO ports on the dumbest
microcontroller, making a much wider range of parts usable
Yes, you're a Luddite :) USB libraries to make a USB interface look like a
virtual UART are well known and work solidly. In Windows/VB, it's called a
MSComm Control and you just drop it into your project and the complexity of USB
disappears. I assume similar mechanisims exist for Linux too.
Regardless, looking forward to seeing what you come up with. I've got a lot to
learn before I can design from scratch an IF strip that works as well as yours
or Ashhar's. And if parts of your design don't quite agree with me, it will be
fun to see if I can do it some other way.
That's what makes the world a better place to live Jerry. I look forward to
meeting your expectations. The big question is what pace will this proceed at?
Jerry, KE7ER
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