AO-91
RADFXSAT · amateur radio satellite, NORAD 43017
Not heard todayAO-91 frequencies
| Uplink | Downlink | Beacon | Mode |
|---|---|---|---|
| 435.250 MHz | 145.960 MHz | — | FM |
| — | 145.960 MHz | — | DUV 200 bd |
Nominal frequencies, without Doppler. The live map shifts them for your station during a pass. Frequencies: SatNOGS DB (modified: working amateur transmitters only, in MHz), CC BY-SA 4.0.
About AO-91
AO-91, built by AMSAT as RadFxSat (Fox-1B), is a 1U CubeSat with an FM repeater and a radiation-effects experiment from Vanderbilt University. It was launched on 18 November 2017 on a Delta II rocket from Vandenberg together with the JPSS-1 weather satellite.
The repeater is a U/v cross-band repeater: transmit on 435.250 MHz FM and listen on 145.960 MHz. Since its batteries degraded it works as a carrier-operated repeater, so no CTCSS tone is needed (a 67.0 Hz tone does no harm). The downlink is on 2 m, so Doppler there is small (about ±3 kHz) and you mostly tune your uplink. When its onboard computer was working, AO-91 also sent low-speed telemetry under the voice (DUV) for AMSAT's FoxTelem software; AMSAT's April 2025 update says it now runs in a basic mode without telemetry.
AO-91 is near the end of its life and works only when the satellite is in sunlight; please do not try to use it in eclipse. Its sun-synchronous orbit brings passes at about the same local times each day, around midday and midnight, and only the sunlit midday passes are usable. A handheld dual-band Yagi and an FM handheld are all you need.
Status
Listed as working, but nobody reported hearing AO-91 on AMSAT in the last 30 days.
From reports filed on AMSAT, last 30 days.
Orbit
| Type | Low Earth orbit |
|---|---|
| Altitude | 423–622 km |
| Inclination | 97.4° |
| Period | 95.1 min |
| TLE epoch | 2026-10-28 14:49 UTC |
Orbital elements: CelesTrak, checked every 3 hours.
Questions about AO-91
- What is the AO-91 uplink frequency?
- AO-91 listens on 435.250 MHz (FM).
- What is the AO-91 downlink frequency?
- AO-91 transmits on 145.960 MHz (FM) and 145.960 MHz (DUV 200 bd).
- Is AO-91 active?
- Listed as working, but nobody reported hearing AO-91 on AMSAT in the last 30 days.
- When does AO-91 pass over my location?
- Open AO-91 on the live map and enter your Maidenhead locator or use GPS: the tracker lists the passes of the next 24 hours with AOS, maximum elevation and LOS, and shifts the frequencies for Doppler.