In Flight Telemetry

[Shazlan]

Dear all,

I'm scouting for information on in flight telemetry system. The study/project is still at its preliminary stage as of now and thus, I do not have much details yet.

The system is to acquire data from sensors as well as images from camera, and transmit these information out to the ground station... and possibly a second aircraft. Acquiring data and images is easy. The concern I have is the size of the information that we plan to telemetry out, which may be up to 170 MB. Question #1: Should the aircraft is flying 5000 ft away from the ground station, how much of a delay we should expect?

I was told that the delay time is highly dependable on the modem capability. Question #2: If so, if we limit the delay to up to 10 seconds (randomly picked), how good, in term of performance, should the modem be?

Question #3: I'm also wondering whether I need to use an external modem for telemetry, or NI has a module that can be used for this purpose?

As noted in my other post, I'm kinda new in this field and will really appreciate any guidelines offered. Thanks in advance.


Shazlan

[Yardov]

Hi Shazlan,

Welcome to the forums. This forum deals with measurements in the radio frequency (RF) and NI does not have a specific RF modem that will help you accomplish what you want (Q#3). Still here are some of my recommendations for your application.

(Q#1) Radio waves travel at light speed c = 10e8 m/s^2, so for 5000 ft (about 1600 m) your signal will take 6 us.

(Q#2) As you mention, if you want your data to take 10 s, and you have 170 MB, then you need to transmit it at about 17 MB/s data throughput. Some modems will spec the overall throughput (including header information) so try to make sure yours is above this number.

Hope these insight helps to get your application planned correctly.