ARISS Voice Uplink Frequency Conflicts with 2 meter WSPR

NEW - Points to consider in resolving the issue of ARISS voice operations in the 2 meter WSPR frequency segment outside of IARU Region 1:

Worldwide 2 meter WSPR activity on 144.4905 MHz has increased over 100 fold in the last 6 months, with operations currently primarily in North America, Europe and Australia. This has increased the potential for mutual interference with the ARISS uplink frequency of 144.49 MHz in IARU Regions 2 and 3. ARISS uses 145.20 MHz for the voice uplink in Region 1.

We have been advised that there is no concern for interference with scheduled event and school voice contacts as ARISS conducts these activities on alternate unpublished uplink frequencies. The ISS team members may use the 144.49 MHz ARISS voice uplink frequency only sporadically for recreational contacts.

AMSAT is interested in this matter, and Frank Bauer, KA3HDO, has related the difficulty with which ARISS coordinated its current frequencies:

"It took a lot of coordination over many years to get SAREX, now ARISS, on a consistent band plan. I have been doing frequency coordination for ARISS and SAREX since 1991. It was very painful to get this coordinated internationally. Especially within Regions 1 and 2. I think you know that ARISS can’t use 145.20 in Region 2.

The big issue we (ARISS) have on 2 meters is that we need the transmit and receive frequencies to be split on voice. And they will need to be separated beyond the OSCAR weak signal subband (145.8-146). This would not have been an issue if the second OSCAR subband (around 144.3-144.5) was still in place. But that was reallocated to other domains."

We would wish to collaborate with AMSAT to avoid interference with future ARISS activity on the 144.49 MHz frequency that we currently share in IARU Regions 2 and 3.

Carol F. Milazzo, KP4MD/W6

144 MHz WSPR Study Spot Database


Some of our 2 meter WSPR study group members have raised concerns about potential interference between 2 meter WSPR operations on our established 144.4905 MHz and the published ARISS Voice Uplink frequency of 144.49 MHz in IARU Regions 2 & 3. The ARISS Voice Uplink frequency in Region 1 is 145.20 MHz.

Here is the status of current IARU 2 meter bandplans:

The IARU Region 1 VHF Bandplan reserves 144.4905 MHz for WSPR -
IARU Region 2 does not yet have a VHF bandplan -
The IARU Region 3 VHF Bandplan reserves 145.8-146 MHz for satellite communication -

As WSPR operation needs to be conducted on common frequencies worldwide to allow propagation studies between IARU regions,
I have referred this matter to AMSAT and WSPRnet for further consideration and advice.

Carol F. Milazzo, KP4MD/W6