⚡ Ham Sat Tracker

Welcome to Ham Sat Tracker

A free, web-based satellite pass predictor built specifically for amateur radio operators. Whether you're chasing SO-50, working the ISS, or planning your next portable satellite activation, Ham Sat Tracker gives you everything you need in one place — including real-time antenna pointing via AntTrack.

Features

• Real-time satellite pass predictions — Know exactly when satellites will be overhead
• Doppler-corrected frequencies — Uplink and downlink at AOS, TCA, and LOS. No mental math required.
• Skyview polar plot — See the satellite's track across the sky for each pass
• AntTrack antenna tracker — Real-time compass-based antenna pointing using your phone's sensors. One tap hands off a pass directly to AntTrack pre-loaded with all pass data.
• Offline capable — TLE data is cached locally so the app works in the field without internet
• Grid square support — Enter your location as a Maidenhead grid square (e.g. FN25) or decimal coordinates
• Mobile responsive — Designed for phone use in the field
• Print friendly — Take predictions to the field on paper if needed
• Light and dark themes — Consistent across the predictor and AntTrack

Free Satellites

• SO-50 (NORAD 27607) — FM voice repeater, 67 Hz CTCSS required
• AO-91 (NORAD 43017) — FM voice repeater (Fox-1B)
• AO-123 (NORAD 61781) — FM voice repeater (ASRTU-1), very active
• ISS (NORAD 25544) — FM repeater and voice
• FO-29 (NORAD 24278) — SSB/CW linear transponder
• RS-44 (NORAD 44909) — SSB linear transponder

AntTrack Pro - $9.99 One-Time

Try free for 7 days — no payment required. Unlock the full toolkit for serious satellite work:

• All satellites — AO-7, AO-73, AO-85, JO-97, SO-125 (HADES), PO-101, XW-2A/B/C/F, LO-94, AO-92, AO-109
• 7-day lookahead — plan your operating schedule for the week ahead
• Date picker — select any future date to see passes for that specific day
• One-tap pass → AntTrack handoff — instantly loads pass data into AntTrack, a mobile antenna pointing tool that uses your phone's compass and tilt sensor to guide you in real time as the satellite moves across the sky
• Pass alerts — 5-minute warning with audio chime before each pass you select
• No ads

Learn more about AntTrack Pro →

How It Works

Ham Sat Tracker uses SGP4 orbital mechanics to predict when amateur radio satellites will pass over your location. For each pass, you get:

• AOS (Acquisition of Signal) — when the satellite rises above your horizon
• TCA (Time of Closest Approach) — maximum elevation point of the pass
• LOS (Loss of Signal) — when the satellite sets below your horizon
• Doppler frequencies — corrected uplink and downlink at AOS, TCA, and LOS
• Azimuth and elevation — where to point your antenna at each point

Getting Started

1. Check out the Beginner's Guide to learn the basics
2. Read more on the blog
3. Learn more about the project

73 and see you on the satellites!
Dave Burniston, VE3AKK

How Amateur Radio Satellite Tracking Works

Amateur radio satellites — called OSCARs (Orbiting Satellites Carrying Amateur Radio) — are small spacecraft built and operated by the ham radio community. Most orbit the earth at low altitudes between 400 and 800 km, completing a full orbit roughly every 90 to 100 minutes. From any fixed point on the ground, a satellite is only above the horizon for about 8 to 12 minutes per pass — which means timing and preparation matter.

Pass prediction uses a mathematical model called SGP4 (Simplified General Perturbations 4) combined with TLE data — Two-Line Elements — published by CelesTrak and AMSAT. TLEs describe a satellite's current orbital parameters: inclination, eccentricity, mean motion. Feed those numbers into SGP4 and you can calculate where the satellite will be at any point in time. Ham Sat Tracker does this calculation locally in your browser using your GPS coordinates or grid square, and shows you every upcoming pass with AOS, TCA, and LOS times.

For each pass, the key numbers are the maximum elevation and the pass duration. A high overhead pass (70°+) gives you the best signal and the most operating time. A low-horizon pass (10–15°) may be blocked by buildings or terrain. In practice, anything above 20° max elevation is generally workable with a handheld yagi or even a well-aimed vertical.

What Is Doppler Shift — and Why Does It Matter?

Amateur satellites travel at roughly 7.5 km/s. As the satellite approaches your position, the received frequency is compressed slightly higher than the transmitted frequency. As it recedes, the frequency stretches lower. This is the Doppler effect — the same phenomenon that makes a passing train's horn change pitch.

On 2 metres and 70 cm — the bands used by most FM satellites — Doppler shift amounts to about ±3–4 kHz across a full pass. For FM satellites like SO-50 and AO-91, this is manageable: tune to the AOS downlink frequency and slowly sweep downward through the pass. For SSB linear transponder satellites like FO-29 and RS-44, Doppler correction is more demanding — even a few hundred hertz of error makes audio unintelligible on SSB.

Ham Sat Tracker calculates the Doppler-corrected uplink and downlink frequency at AOS, TCA, and LOS for every pass, so you know exactly where to start and where you'll end up. No mental math, no frequency charts taped to your radio. Read more in the Doppler shift guide.

Which Satellites Should You Start With?

If you're new to satellite operating, start with the FM voice repeater satellites. They work just like a terrestrial repeater — key up, speak, unkey — except the repeater is 500 km overhead and moving at 27,000 km/h.

SO-50 (NORAD 27607) has been in orbit since 2002 and remains one of the most reliable FM satellites. It operates on a 145.850 MHz uplink and 436.795 MHz downlink, with a 67 Hz CTCSS tone required to open the squelch. A brief 74.4 Hz burst activates the satellite's 10-minute timer if it has gone dormant. SO-50 is active daily and regularly used by operators from handheld radios in the field.

AO-91 (NORAD 43017, Fox-1B) is a strong signal satellite with a 145.960 MHz uplink and 435.250 MHz downlink. No CTCSS required. AO-91 is solar-powered, so it's only active in sunlight — passes in eclipse produce no signal.

AO-123 (NORAD 61781, ASRTU-1) launched in 2024 and has become one of the most consistently active FM satellites currently on orbit. 145.850 MHz uplink, 435.400 MHz downlink, 67 Hz CTCSS.

Once you're comfortable with FM satellites, FO-29 and RS-44 open up SSB and CW operation — linear transponders that carry dozens of simultaneous contacts across a 100 kHz passband. A completely different operating experience, and enormously satisfying. The best satellites for beginners guide covers all of these in detail.

What Equipment Do You Need?

For FM satellites, the minimum working station is a dual-band radio capable of split operation (transmitting on one band while receiving on another simultaneously) and a handheld yagi antenna. A Yaesu FT-60, Kenwood TH-D75, or even a Baofeng UV-5R will work for receive — though the Baofeng struggles with full-duplex monitoring of your own signal. The antenna is often more important than the radio: a 3-element handheld yagi makes an immediate difference over a rubber duck.

I do all of my satellite work QRP portable as I live in a high-rise apartment — typically with a Yaesu FT-818ND and a handheld Arrow-style yagi antenna. What matters is pointing the antenna correctly and knowing when the bird is up. That's what the tracker is for.

For SSB satellites, you'll want a radio with genuine split-VFO capability and 100 Hz tuning steps. A mode-capable radio like the Yaesu FT-818, IC-705, or KX3 is the standard choice. The equipment guide covers everything you need for both FM and SSB work.

Portable Satellite Operating

One of the most enjoyable aspects of amateur satellite operating is its portability. Everything you need fits in a small bag: a dual-band HT, a collapsible yagi, a phone running Ham Sat Tracker. Parks, hilltops, rooftops — anywhere with a clear sky view in multiple directions works. Because the satellite is moving across the sky, you're sweeping the antenna through about 180° of arc over 8–10 minutes, which means obstructions matter less than for fixed-station HF work.

A typical portable satellite session: open Ham Sat Tracker, enter your grid square, check the next 2–3 passes. Arm a 5-minute alert on the best pass. When the chime fires, take your radio outside, set your frequency to the AOS values, point the antenna toward the AOS azimuth, and wait. Within 30 seconds of AOS you should hear the satellite — either the beacon or other stations already working through it.

The QRP satellite operations guide goes deeper on low-power portable technique, and the FAQ covers the most common questions about getting started.

Do I Need a Licence?

Yes — transmitting through amateur satellites requires an amateur radio licence. In most countries, a Technician class licence (USA) or equivalent entry-level licence is sufficient to operate on the 2-metre and 70-cm frequencies used by FM satellites. You can receive satellite signals without a licence — and listening to passes is a great way to learn before you transmit.

If you're already licensed, Technician class in the US gives you full privileges on the satellite bands. The Technician licence guide explains exactly what privileges apply to satellite work and what to expect from your first passes.

73 and good DX — see you on the satellites.
Dave Burniston, VE3AKK