The Ku-band system consisted of a directional antenna mounted in the orbiter payload bay and provided high BW communication with a ground station. This page: KU-BAND SYSTEM describes the system as having uplink at 13.755 GHz and downlink at 15.003 GHz. The various modes and data rates are described as well, but there is no mention of the modulation / coding that was used. There seem to be a few IEEE articles that may explain the system in detail, however they require purchase. My guess is it should have been PM, but if someone could confirm it would be great.

  • $\begingroup$ I can't make heads or tails of it (I don't speak comm) but I bet your answer is in here nasa.gov/centers/johnson/pdf/… starting on page 2.4-13 $\endgroup$ Nov 18, 2015 at 22:42
  • $\begingroup$ @OrganicMarble Thank you for the link. The information on the topic is roughly the same as the link in the Q. Unfortunately, no mention of modulation. Which is odd, since the details for this are given for the S-band system. $\endgroup$
    – Kamen N.
    Nov 18, 2015 at 23:07

1 Answer 1


I am not very comm literate but hopefully I can parrot this information about TDRSS Ku-band modulation I found and point you to the source so that you can confirm whether or not it actually answers your question.

This document states

The K-band SA forward link is the only service for command data greater than 300 kbs and its carrier is BPSK modulated without range channel transmission.

Where SA stands for Single Access and BPSK stands for BiPhase Shift Key. (Italics mine).

For Multiple Access (MA) service this table is provided:

enter image description here

  • $\begingroup$ The operations manual pdf that you linked in your comment is quite a good read! I noticed that it makes a distinction between digital and analog TV, for example starting on page 2.3-1. Then in the Ku-band section, in the 2nd column of page 2.4-13 it describes the band being separated into three channels, and there are used differently in Mode 1 and Mode 2. In Mode 2, Channel 3 is for analog video. $\endgroup$
    – uhoh
    Oct 9, 2017 at 1:45
  • $\begingroup$ I'm no expert in this at all, but for analog video not coming from digital video cameras, there may not be any digital modulation or encoding whatsoever in the transmitted signal in Channel 3, when operated in Mode 2. $\endgroup$
    – uhoh
    Oct 9, 2017 at 1:48
  • 1
    $\begingroup$ I don't understand any of this, not even enough to know if it answers the question. I just was browsing that TDRSS document and saw the word modulation. $\endgroup$ Oct 9, 2017 at 1:49
  • 1
    $\begingroup$ I love reading things that are written with utmost clarity and no ambiguity. Good documentation-writing is somewhere between an art and a science, and large projects live or die on the quality of their documentation. $\endgroup$
    – uhoh
    Oct 9, 2017 at 1:55
  • 1
    $\begingroup$ That's one of the very best publicly available documents on Shuttle technical details - it was written for the crew! And kept up to date, too - we updated it every time a new flight software Operational Increment came out. $\endgroup$ Oct 9, 2017 at 1:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.