# What is the range of frequencies of a deep space channel?

I've been trying to find the values of bandwidth of each Deep Space frequency channel: band S, X and Ka. In the official NASA's documents only appears the center frequency of each one, but it doesn't describe their range. Do you know if there is any page where I can find those values?

• The DSN Now page shows information on communications currently in progress. Press "more detail" and scroll the information in the lower-right side; you can see the carrier frequencies used for the selected spacecraft. It doesn't tell you the bandwidth, and it is limited to those spacecraft currently in contact, but at least it gives some information you are looking for. Sep 9, 2021 at 4:01
• Somewhere in the DSN Telecommunications Link Design Handbook you will find the answer Sep 9, 2021 at 11:37

The full range of the bands are 2 to 4 GHz (S), 8 to 12 GHz (X), and 27 to 40 GHz (Ka); see Wikipedia IEEE radar bands for the whole list.

DSN uses only a small fraction of those ranges. For example, in S band, DSN stays inside 2025 to 2120 MHz and 2200 to 2300 MHz, but doesn't fill it everywhere (part of that is unused by the Madrid station due to interference). See JPL 810-005 201, Rev. D for the rest.

Even that is a gross oversimplification, because all of these bands are licensed for multiple uses. What the S band portion really looks like, at least in the U.S., is this: , taken from this chart.

The individual channels into which each DSN band is divided are expressed by a page of formulas which may be found in the same JPL document I linked above. It begins with:

The S-band downlink center frequency (Fch(14) = 2295 MHz) is used to derive all entries in the tables using the expressions Fch(n) = (n-14)*(10/27) + 2295 MHz, rounded to the nearest Hertz where Fch(n) is the center frequency (in MHz) of channel n rounded to the nearest Hz, and the ratio 10/27 is the spacing (in MHz) between the centers of two adjacent channels.

10/27 MHz means each DSN channel is centered 370 kHz apart, but that still doesn't tell us how much of that width is actually occupied by the modulation in use. A different JPL document in the same series, 810-005 206, Rev. C, says that is user-selectable, using BPSK rates of 4 kbps to 256 kbps, and a wide variety of error correction encodings.

Thank you, all of you.

According to your valuable responses, I found the following bandwidths for each Deep Space allocated frequency channel:

1. S-band --> 370 kHz/channel
2. X-band --> around 1.4 MHz/channel
3. Ka-band --> around 5 MHz/channel
• In downlink (telemetry)** Sep 9, 2021 at 19:47