What do you make of this at 1100mhz

Those of us who already commented here mustn’t be “cool”?.. :wink:

Any autoscaling on these graphs makes the “with” and “without filter” comparisons less useful. A fixed scale (one that identifies SNR by color intensity) would be preferable. Ideally they’d use the full spectrum of color to denote intensity (I’m thinking like a weather radar map)…

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urm, I don’t think I can move it…unless a mod/admin can?

@wiedehopf - being able to disable autoscale and set max/min would be very handy! TIA if you do it. :grin:

I checked the Aliexpress above site.
Although the photo displayed with option “with battery” shows a VNA in a black plastic case, there is no mention of case (in writing) anywhere. I was about to order it, but stopped as I dont want one without a case. I will wait till you receive it and tell if the “with battery” option you ordered is with or without case.

The photos for option “without battery” clearly shows no case is provided.

Without Battery option



With Battery Opotion


How do I run those scans on a mac, I have the FA pro stick?


I’ve moved it.

Assuming it’s Kyle Keen’s heatmap.py, there is a --db-limit arg for a fixed intensity scale



Yes, it is…




pi@raspberrypi:~ $ ./heatmap.py -h  
usage: heatmap.py [-h] [--offset OFFSET_FREQ] [--ytick TIME_TICK]
                  [--db DB_LIMIT DB_LIMIT] [--compress COMPRESS]
                  [--low LOW_FREQ] [--high HIGH_FREQ] [--begin BEGIN_TIME]
                  [--end END_TIME] [--head HEAD_TIME] [--tail TAIL_TIME]
                  [--palette PALETTE]
                  INPUT OUTPUT

Convert rtl_power CSV files into graphics.
positional arguments:
  INPUT                 Input CSV file. (may be a .csv.gz)
  OUTPUT                Output image. (various extensions supported)

optional arguments:
  -h, --help            show this help message and exit
  --offset OFFSET_FREQ  Shift the entire frequency range, for up/down
  --ytick TIME_TICK     Place ticks along the Y axis every N
                        Minimum and maximum db values.
  --compress COMPRESS   Apply a gradual asymptotic time compression. Values >
                        1 are the new target height, values < 1 are a scaling
  --palette PALETTE     Set Color Palette: default, extended, charolastra,

  Efficiently render a portion of the data. (optional) Frequencies can take
  G/M/k suffixes. Timestamps look like "YYYY-MM-DD HH:MM:SS" Durations take
  d/h/m/s suffixes.

  --low LOW_FREQ        Minimum frequency for a subrange.
  --high HIGH_FREQ      Maximum frequency for a subrange.
  --begin BEGIN_TIME    Timestamp to start at.
  --end END_TIME        Timestamp to stop at.
  --head HEAD_TIME      Duration to use, starting at the beginning.
  --tail TAIL_TIME      Duration to use, stopping at the end.

@abcd567 Amazing help, thanks! Incidentally, any insight on what the various color palette options mean?

I’m not sure what the attachment is for those plots? Why not run Spektrum?


Then can properly tweak gain/scale as you go and won’t need to rely on a script to run for hours.

ADD: This is obviously from a Winblows setup - I guess I understand the need for some to need to run on their Pi, but it’s another option I guess.


The point of running data collection for hours is to collect data over a span of hours, not a single snapshot.


Agreed, and there are good reasons for that. The newer version of Spektrum has avg and smoothing if needed to run for a long period of time. Just an idea for those who may not have tried or heard about it before, - another tool in the box for perspective.


Those yellow colored scans are generated by running rtl_power followed by running heatmap.py.

I tried Spektrum on Windows. Nice GUI. Could not fully expkore its capabilities and how to use it. Will do it when find time.

That is why for Windows, I have proposed using rtlplan.exe, which gives both the heatmap and instanteneous plot on x-y graph.

What values for min & max DB_LIMIT do you suggest for --db argument?


You’ll have to work that out from your data.

I’m not even sure which range is being used.
Check the csv file maybe?

The range used is shown in the output from the heatmap command as the z parameter
It finds the highest and lowest figures in the csv and uses them.
eg from a scan I did:
./heatmap.py scan.csv scan.png
x: 4576, y: 60, z: (-37.070000, 4.400000)

I suggest using something like -40 to 10 as a fixed scale so:
./heatmap.py --db -40 10 scan.csv scan.png

No idea. Just a guess that default is yellow, and other colors in the list can be chosen instead of yellow by adding that argument (for example --palette twente) in the command.

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