Non-coherent spread spectrum for distance measurement

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Discussion Overview

The discussion revolves around the technology of non-coherent spread spectrum for measuring distances, particularly in the context of satellite and ground station communication. Participants explore various systems and methodologies related to distance measurement, including their applications and implementations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants mention non-coherent ranging systems, including travel time ranging and telemetry aided Doppler tracking (TADT), as relevant technologies.
  • There is a suggestion to explore regenerative ranging and pseudo-noise ranging systems, with references provided for further reading.
  • One participant expresses interest in understanding the technology better through practical implementation, noting the challenges in finding information due to the niche nature of the field.
  • A participant describes a method for conducting experiments with pseudorandom binary sequence (PRBS) ranging codes, suggesting that these can be used to measure distance without transmission.
  • Another participant raises a question about the feasibility of using onboard GPS equipment in flying objects for distance calculation, prompting a discussion on the context and objectives of the measurement.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for distance measurement, as opinions vary regarding the effectiveness of non-coherent spread spectrum versus onboard GPS systems, depending on specific use cases.

Contextual Notes

Participants acknowledge the complexity of the field and the potential limitations in available resources and information regarding non-coherent spread spectrum technologies.

senmeis
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Hi,I’ve heard of a technology that enables to measure the distance of a satellite to the ground station by using non-coherent spread spectrum. Can anybody tell me what’s the name of this technology?Senmeis
 
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Non-coherent Ranging Systems.

Travel time ranging. Time delay ranging.

Telemetry Aided Doppler Tracking. (TADT).

Regenerative ranging. Pseudo-noise ranging systems.
Regenerative Pseudo-Noise-Like (PNL) ranging sequences
https://public.ccsds.org/Pubs/414x0g2.pdf
 
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Thank you. It seems similar to range measurements in GPS. Where can I find some products providing this mechanism?Senmeis
 
Exactly what are you trying to do ?
 
I want to understand this technology, but with the implementation I will get a better understanding. I know this is a relative small application field so it’s not easy to find such info in internet.Senmeis
 
senmeis said:
I know this is a relative small application field so it’s not easy to find such info in internet.
The problem is with the huge size and complexity of the fascinating field.
Google ' introduction to spread spectrum .pdf '

https://en.wikipedia.org/wiki/Pseudorandom_binary_sequence
You can conduct experiments with PRBS ranging codes on the bench or in coaxial cables without needing to transmit. If you make PRBS generators and clock them at slightly different rates, they will regularly move through synchronisation which you can detect with a simple phase detector such as an EXOR gate and low pass filter. In effect the PRBS code is a uniquely coded tape measure that is fed to a transponder and back again. By measuring the transit time you measure the distance.
 
Thank you. I think I can understand this technique. What about the case if the flying object has its own onboard GPS equipment? The distance can be calculated if the flying object’s coordinate is broadcasted. Is it a better way?Senmeis
 
senmeis said:
Is it a better way?
It will depend on what you are trying to do and why you are doing it.
 

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