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Yes, should be possible.? Note this is for a homebrew version based on ESP32 processor, not the tinySA developed by Erik/Hugen.

The firmware already allows use of the main SA RF connection as a signal generator.? The frequency range will depend on the low pass filter components installed, typically up to 200/250MHz but it should be possible to design for higher cut off, say up to 350MHz, we have not tested that yet.? Output level can be adjusted using the attenuator and varying drive strengths from the SI4432.

The tracking generator based on two SI4432 should be capable of the same performance, and indeed adding a signal generator facility for the TG is already on the ToDo list.? Note that the frequency resolution of the SI4432 tranceiver module limits the resolution of the output frequency.? With a nominal 434MHz IF, the resolution is 156Hz below 46MHz output and 312Hz above that.? Not sure if that is good enough for your needs.? The oscillator in the SI4432 modules can also drift badly - not so bad given the resolution available, but could be a problem in certain cases.

Also currently there are no modulation options programmed in the firmware, though again this is planned.? AM is likely to be fairly crude!

There are options to improve performance - a TCXO could be used for example, different tranceiver modules such as SI4468 are available with finer frequency resolution (14.3Hz), or a suitable low phase noise clock generator ic could be selected.

Dave M0WID

The tinySA I designed is able to act as a signal generator.
See here for the specs:?
--
HBTE Files section:?/g/HBTE/files
Erik, PD0EK

Is the tracking generator able to also ( with appropriate firmware) be a useful stand-alone rf signal generator?

I had asked a question on the Homebrew (I think) group if any enterprising designer was interested in a Tinysa- type signal generator to complete the stable of this fantastic set of affordable gear. The tracking generator seems to be already half the device ( including an attenuator to adjust the output signal).

I do not think my design skills ( not to mention programming ability) ate up to it, even with a “starter for 10 board potentially available.

Steve L. G7PSZ

Another option to improve the RBW might be to use the SI4468 as the receiver.? These are ?2.52 plus VAT from Mouser UK in single units

According to the datasheet the digital filters can be set to minimum 0.21kHz bandwidth, and 0.26, 0.28, 0.32, 0.39, 0.48, 0.54, 0.81, 0.89, 0.96, 1.19kHz etc also seem to be available.? Frequency resolution also seems to be better than the SI4432.

Working out how to program the thing looks to be a nightmare however, definitely more complicated than the SI4432.? The narrow bandwidths would almost certainly need a TCXO to be worthwhile, and of course the pin outs are different.
Reading RSSI on wide bandwidths could also be slower extending the sweep times.? How it actually works in practice and how good the filters and RSSI readings really are will need testing.

I have ordered one to play with, but I am really busy so it will take some time before I get round to it.

Dave

A low cost FPGA would be my choise as well.?
I was unaware of the evaluation board, but would have used sata cables on my planed test board.?
They just are so cheap and convenient.?

The hackRF sdr radio uses a somewhat similar construction.?
A xilinx cpld is used between the nxp lpc series mcu and the maxim analog baseband chip.

As for stm32f4's adc, its only 7msps in interleaved mode.
Without interleaving it's only 2.4msps.?
But that would be enough with an IF slightly below 1.2MHz

hello all,
hello ismo,

thanks for the answer.
i have no experience with LVDS buses

but i can see the numbers: 4MSaps*13bit/Sa*2channels=104Mbps
the chip evaluation board uses two SATA connectors for this high speed bus: clk+rx and clk+tx
unfortunately, i can not find this kind of interface in the now common STM32 microcontrollers.

maybe using a 3EUROs-FPGA ;-) you can merge:

1)a LVDS+DDR reception interface,
2)a cascade of CIC decimatig filters
3)the operation i*i+q*q
4)a interface with the microcontroller

the microcontroller finishes the signal processing

5)operation SQRT(x)
6)averaging (videobandwith) filter, VBW? (trick RBW=3*VBW)
7)operation log10(x) to present the information in a logarithmic scale

this solution means, at least, 3EUR plus some knowledge of verilog and current synthesis tools

==
sounds interesting, but...
i will prefer a more analog solution:
a double conversion superhetereodyne 434.2MHz receiver with a second IF in 1.2MHz
this IF can be sampled by a STM32F4xx 7Msps 12b ADCs,
with the same steps 1-7 but implemented a C program.

73 from eduardo, ea3ghs

I just wish the the ship was not 25usd for a 20usd book.
And if add another book it rises to 35usd!

Hi,

Generally the ARRL will sell materials to anybody who wants to buy them. ARRL also has some materials on their web site that are free for everybody to use. There are or have been some items that cost less for members than for non members. Reprints of articles come to mind. It is probably not reasonable for hams in other countries to join the ARRL (although some do). But you are looking for information don't bypass the ARRL web site just because you are not a member. If you look there and membership is required it will just tell you that. Nothing harmed. If membership is not required it will send the requested information.

73,

Bill KU8H

bark less - wag more

On Thu, Aug 27, 2020 at 01:11 PM, Jim Strohm wrote:

Or SPAM victims ....

How about explaining your specific issues?? Is this not a forum for discussing homebrew test equipment?? The very first chapter has a section on measuring RF power including building power meters and an RF probe.? Seems to me this is exactly the type of book that belongs here.

On Thu, Aug 27, 2020 at 01:08 PM, MVS Sarma wrote:

Only for arrl members i supose

I am not a member and had no problem ordering.

Great opportunity to get this classic book.?

Immerse yourself in the communications experience. Build equipment while understanding basic concepts and circuits.

Clearance stock-out price!

Item No. 1017 -?$20.00

?

I have done some datasheet reading on the AT86RF215M, but mostly as a solution for low cost sdr uses, not as a spectrum analyzer IF :)
The annoying bit about it is the interface via which the IQ samples flow.?
It's a 128mbps LVDS interface with a 64MHz clock as it samples on both clock edges, being DDR.
So even if the samplerate is only 4MSPs, the datarate is much higher.?
I have so far contemplated using a small FPGA or CPLD as the glue logic from it to an mcu like nxp i.mx rt crossover series or stm32f7.?
As the annoying DDR clock won't work with most SPI peripherals or other similar existing interfaces.
On the the bright side one could decimate in the FPGA, so there's that.

-Ismo

hello all,

i just discovered this group and their efforts...
congratulations for the SA analyzer and its fantastic price.
you have killed to us the desire of design/build our own SA, hi hi

i can not find the schematic anywhere, so i will talk in reference i could see in

http://www.carnut.info/tinySA/tinySA.html
https://www.changpuak.ch/electronics/Arduino-Project-VISIONARY.php

from my point of view, the worst performance of the SA is RBW, limited by the receiver channel bandwidth.

for a communications application, during some time i have been looking "one-chip" transceiver
with a very narrow channel bandwidth. in fact I landed here to discover which chip you were using...

well, some weeks ago I found this chip:

AT86RF215M
3.03EUR@25UNITS in MOUSER
http://ww1.microchip.com/downloads/en/devicedoc/atmel-42415-wireless-at86rf215_datasheet.pdf
AT86RF215 / AT86RF215IQ / AT86RF215M
Sub-1GHz/2.4GHz Transceiver and I/Q Radio

where you can extract the zeroif IQ data stream 13+13bits with a sampling frequency of 4Msps max.

i am not sure if you need some other functionality in the SI4432 "one-chip" transceiver,
but it seems a good idea to connect AT86RF215M to a STM32F4? and, doing decimation, improve the
dynamic range and RBW (1bit more reducing 4 times the sample speed)

some devices of the STM32F family include a delta-sigma digital filter ("DS demodulator")
it is not very well documented for this purpose, but it seems possible to do decimation by hardware.

well, this is my 2cents to this nice project that it will save a lot of time to lots of people

73 from catalonia,
ea3ghs eduardo

The V2.0 panels have been loaded and tested in the Tracking Gen mode. Very promising.? Note no shielding was fitted anywhere in this test. (with some small mods for chip selects, V1.0 panels should work too.)

Comparison with my Rigole on testing a junk box High Pass Filter look promising.?? The roll-off at the high end maybe due to the Si4342 module LPF filters which can be bypassed. Will look at that later but the concept is proven.? It uses 1 x control board (top of the panel and two x RF boards, so two panels are needed.

Many thanks to M0WID, WA2FZW & G3ZQC for software.

Glenn

After being on hold, my new "V2" panels have arrived.? These are slightly modified V1.0 versions to provide for a tracking generator option once software is fully developed for it.

Glenn
vk3pe