[TangerineSDR] Notes from PSWS / TangerineSDR call of 12-02-2019

[Tom McDermott]

HI Phil, Attached is the group delay curve for the 40 MHz filter.  It's
pretty flat up to about 50 MHz then
climbs in the 6M band. The 50 MHz filter has a different shape, but is
within +/- 3 nsec through
55 MHz., a lot less delay.   The 50 MHz filter probably doesn't require
delay compensation, the 40 MHz does for
measurements above about 45 MHz.  8 nsec is one ADC clock sample time.

The much bigger concern is the AM broadcast bandstop filter. That has very
non-linear phase from about
1.8 MHz downwards. Above 1.8 MHz the delay drops and flattens out. That
filter will be much more sensitive
to component variation, so it will need to be calibrated on a per-filter
basis.

-- Tom, N5EG
[image: Screenshot from 2019-12-03 07-45-56.png]





On Tue, Dec 3, 2019 at 3:29 AM Phil Erickson <phil.erickson at gmail.com>
wrote:

> Hi all,
>
>   Sorry that I was not able to join the call last night.
>
> 1. Receiver: 40 MHz LPF filter is preferred by the group. The loss at 6M
>> is a little higher, but likely will need an LNA for 6M use anyway, so that
>> may not matter. The nearby-above-61 MHz loss is better with the 40 MHz
>> filter. Also include jumpers for power and ground bonding and for use by
>> some future low-noise amplifier.
>>
>
>  One point not brought up in this sentence:  the phase response of the LPF
> above its cutoff will not necessarily be linear.  Was that discussed?  It
> might impact any use at 50 MHz, or at the least would require careful
> calibration if it were to be used there.
>
> 73
> Phil W1PJE
>
>
>
> On Mon, Dec 2, 2019 at 10:11 PM Tom McDermott via TangerineSDR <
> tangerinesdr at lists.tapr.org> wrote:
>
>>
>> Notes from PSWS / TangerineSDR call of 12-02-2019
>>
>> 1. Receiver: 40 MHz LPF filter is preferred by the group. The loss at 6M
>> is a little higher, but likely will need an LNA for 6M use anyway, so that
>> may not matter. The nearby-above-61 MHz loss is better with the 40 MHz
>> filter. Also include jumpers for power and ground bonding and for use by
>> some future low-noise amplifier.
>>
>> 2. Dave W. recommends putting pads for a low cost I2C temperature sensor
>> on the magnetometer module just in case the PNI-3000 has temperature
>> sensitivity and needs compensation. Scotty recommends adding a strap to one
>> of the temperature sensor address lines so that sensors on the local and
>> remote ends can be separately addressable.
>>
>> 3. We currently do not have a logo for the Personal Space Weather
>> Station. Would such be useful? Dave L., Scotty, and Nathaniel will add some
>> material to the tangerinesdr.com webpage tying the various parts of the
>> project together.
>>
>> -- Tom, N5EG
>>
>> --
>> TangerineSDR mailing list
>> TangerineSDR at lists.tapr.org
>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org
>>
>
>
> --
> ----
> Phil Erickson
> phil.erickson at gmail.com
>
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