General
Is Ham Sat Tracker free?
Yes — the core predictor is completely free with no account required. Every new visitor also gets a 7-day free trial of AntTrack Pro automatically, with no payment or sign-up needed. After the trial, the free tier covers the five most popular satellites with 24-hour predictions, Doppler frequencies, skyview plots, and AntTrack antenna pointing.
AntTrack Pro is a one-time $9.99 upgrade that unlocks all satellites, 7-day lookahead, date selection, one-tap pass handoff to AntTrack, pass alerts, and removes ads.
Do I need to create an account?
No. Ham Sat Tracker works without any account or login. Your location and preferences are saved locally in your browser.
Does it work on mobile?
Yes — it's designed primarily for phone use in the field. AntTrack's compass-based antenna pointing specifically requires a mobile device with a magnetometer (compass) and accelerometer (tilt sensor). Most modern smartphones have both.
Can I install it as an app?
Yes. On Android, open the site in Chrome and tap Add to Home Screen from the browser menu. On iOS, open in Safari, tap the Share button, and choose Add to Home Screen. The app will appear as an icon and open without the browser chrome.
Pass Predictions
How accurate are the predictions?
Pass times are accurate to within a few seconds when TLE data is fresh (less than a few days old). Accuracy degrades gradually with older TLEs — predictions with data more than 7 days old should be treated as approximate. The header shows the age of your current TLE data.
Why does the app show no passes?
A few common reasons:
- Minimum elevation is too high — try lowering the slider to 5° or 0°
- Time range is too short — some satellites have long gaps between passes from a given location. Try 24h or longer.
- Location is wrong — double-check your grid square or coordinates
- The satellite is genuinely inactive — some birds have periods of inactivity. Check AMSAT Satellite Status for current activity reports.
What does max elevation tell me?
Max elevation is the highest point the satellite reaches during the pass. Higher is generally better — a pass at 70° max elevation gives you much more time in the usable part of the sky than a 15° pass. For FM satellites, anything above 20° is usually workable. Below 10° is often blocked by obstructions or too brief to be useful.
Why do some passes start or end at odd azimuths?
The AOS azimuth is where the satellite crosses your minimum elevation threshold — not necessarily due North or South. Satellites cross the sky at all angles depending on their orbital inclination and your latitude. The skyview polar plot on each pass card shows the full track visually.
Can I see passes for a specific future date?
Yes, with AntTrack Pro. The date picker lets you select any future date and see all passes for that day's window. Useful for planning a portable activation days in advance.
Doppler and Frequencies
What are AOS, TCA, and LOS frequencies?
These are the uplink and downlink frequencies corrected for Doppler shift at three points in the pass:
- AOS (Acquisition of Signal) — as the satellite rises. It's approaching, so the downlink is slightly higher than nominal and the uplink slightly lower.
- TCA (Time of Closest Approach) — the peak of the pass. Doppler shift is near zero, so frequencies are closest to the nominal values.
- LOS (Loss of Signal) — as the satellite sets. The reverse of AOS — downlink drops below nominal, uplink rises.
For FM satellites, start at the AOS downlink frequency and tune it slowly downward throughout the pass. For SSB linear transponders, continuous tuning is more critical — keep your own signal in position on the transponder passband.
My radio doesn't have the exact frequency shown — what do I do?
Round to the nearest 5 kHz for FM satellites — this is close enough. For SSB work, tuning in 100 Hz steps is ideal. The frequencies shown are calculated values; in practice you'll be tuning by ear anyway.
Why do I need a CTCSS tone for SO-50?
SO-50 requires a 67 Hz PL (CTCSS) tone on the uplink to open the repeater's squelch. Without it the satellite won't hear you even if your signal is strong. Program 67 Hz into your radio before the pass. If the satellite seems unresponsive, try a brief transmission with 74.4 Hz — this activates the satellite's 10-minute on-timer if it has gone to sleep.
TLE Data
What are TLEs?
TLE stands for Two-Line Element set — a standardised format for describing a satellite's orbital parameters. The predictor uses TLE data to calculate where each satellite will be at any given time. TLEs are published by CelesTrak and updated regularly as satellites experience small orbital changes due to atmospheric drag and other forces.
How often should I update TLEs?
For casual use, once a week is fine. For critical portable planning or when a satellite has recently manoeuvred, update before each session. The app does this automatically each time you load it if you have internet access.
Will the app work without internet?
Yes. TLE data is cached locally after each successful fetch. If you're in the field without cell service, the app uses the cached data and shows a banner telling you how old it is. For best results, tap Update TLEs before leaving home.
Pass Alerts
How do pass alerts work?
Each pass card has a 🔔 Alert button (Pro feature). Tap it to arm a 5-minute countdown before AOS. When the timer fires, an amber banner appears at the top of the page and a three-tone chime plays. Tap the button again to cancel. Multiple passes can be armed simultaneously — each has its own independent timer. Alerts require the page to stay open in your browser.
The chime isn't playing on my phone — what's wrong?
Mobile browsers require a user interaction before allowing audio to play (browser autoplay policy). Since you tap the Alert button to arm it, that interaction should be sufficient. If the chime doesn't play on the first try, arm the alert and then tap any button elsewhere on the page before the timer fires — this confirms the audio context to the browser and resolves the issue.
AntTrack Antenna Pointing
What is AntTrack?
AntTrack is the antenna pointing tool built into Ham Sat Tracker. It uses your phone's compass and tilt sensor to show real-time azimuth and elevation guidance during a satellite pass — so you know exactly where to point your antenna.
Why is my compass reading wrong?
The most common cause is that the phone's compass needs calibration. Before opening AntTrack, wave your phone in a figure-8 pattern for a few seconds outdoors — this resets the magnetometer. Other causes:
- Being indoors — building materials, wiring, and metal structures significantly deflect the compass
- A magnetic phone case — remove it before operating
- Metal vehicles or structures nearby — step away by at least a few metres
- No GPS fix — without GPS the phone may use magnetic north rather than true north, which is about 12° off in Ottawa
On iPhone, AntTrack shows a CMPS ±N° indicator in the status bar. If it shows red (±20° or worse) the compass needs calibration before the pass. Close AntTrack, do the figure-8 gesture, and reopen.
How do I know if my compass is accurate enough?
On iPhone, watch the CMPS dot in AntTrack's status bar. Green (±10° or better) means the compass is reliable. Amber (±11–20°) is marginal. Red (±20° or worse) means the compass readings won't be useful — do a figure-8 calibration gesture before proceeding. If compass accuracy is poor when GPS first locks, AntTrack will show an amber warning banner automatically.
On Android this accuracy reading isn't available, so use the figure-8 gesture as standard practice before every session regardless.
What does the elevation calibration step do?
When you enter the tracking screen, AntTrack shows a live tilt reading in degrees. Point your antenna boom at the horizon (0° elevation) and watch the number — when it settles near 0° and the display turns green, tap Calibrate. This zeros the tilt sensor for your specific phone mounting position so elevation readings are accurate throughout the pass.
The live reading updates 10 times per second. Watch for it to stabilise before tapping — if the number is jumping around, hold the antenna steadier.
Can I use AntTrack without a directional antenna?
AntTrack is most useful with a directional antenna like a handheld yagi or Arrow antenna where pointing matters. With an omni antenna there's nothing to point, though the elevation indicator can still tell you when the satellite is high enough to be worth listening for.
AntTrack Pro
What does AntTrack Pro include?
- All satellites — full list including AO-7, AO-73, JO-97, SO-125 (HADES), PO-101, and more
- 7-day pass lookahead
- Date picker — select any future date
- One-tap pass handoff to AntTrack (pre-loaded with all pass data)
- Pass alerts — 5-minute warning with audio chime before each pass you select
- No ads
Is it a subscription?
No. AntTrack Pro is a one-time payment of $9.99. No renewals, no recurring charges.
How does the free trial work?
Every new visitor gets 7 days of full Pro access automatically — no payment, no sign-up, nothing to click. All Pro features are active from the moment you first open the tracker. A green banner shows how many days remain. When the trial ends the tracker reverts to the free tier and an amber banner invites you to upgrade. The trial is stored in your browser so it resets if you clear your browser data — but not if you use the site regularly.
How does activation work?
After payment, Stripe redirects you back to the site where Pro is activated automatically in your browser. No account is created. Your activation is stored locally on your device.
Can I use Pro on multiple devices?
Yes. Your purchase confirmation email includes a restore link. Open it on any device to activate Pro on that device.
What happens if I clear my browser data?
AntTrack Pro activation is stored in your browser's local storage. If you clear your browser's site data, cookies, or local storage, Pro will be deactivated on that device. To restore it, use the restore link from your purchase confirmation email. If you activated via a beta access token, contact us and we'll send you a fresh activation link.
My Pro status keeps disappearing on iPhone — why?
There are two separate issues on iPhone:
1. Safari vs Home Screen app have separate storage. When you add the site to your Home Screen and open it as an app, iOS gives it completely isolated storage from Safari. Pro activated in Safari won't carry over. The fix is simple — after adding to Home Screen, open the app and go to beta-access.html to enter your token again. The tracker will show an amber banner reminding you to do this the first time it opens without Pro.
2. Safari clears localStorage after 7 days. iOS Safari automatically clears website storage for sites not visited recently as part of its tracking prevention policy. When running as a Home Screen app this doesn't apply — another reason to use the Home Screen app rather than Safari directly.
Recommended workflow: Add to Home Screen first, then activate Pro from within the app. After that, Pro and your grid square will persist reliably.
I'm a beta tester — will my Pro access continue after the beta ends?
Yes. Beta access tokens activate Pro locally on your device the same way a paid activation does. When the public beta ends your Pro access remains active as long as you haven't cleared your browser data. If you lose access for any reason, contact us and we'll sort it out.
I lost my confirmation email — how do I restore Pro?
Use the contact form with your order details and I'll sort it out.
Satellites
Why isn't [satellite] in the list?
The satellite list is curated to include only currently active birds with recent operating reports. Satellites that haven't been heard from reliably are removed to avoid showing passes for birds that aren't working. If you think a satellite should be added, let me know — I check the AMSAT Satellite Status Page regularly to keep the list current.
The ISS repeater isn't active during the predicted passes — why?
The ISS ARISS repeater is not always on. It operates on a schedule determined by the crew and ARISS, and is sometimes off for extended periods. Ham Sat Tracker shows ISS passes based on orbital mechanics regardless of repeater status. Check ariss.org for current status before planning an ISS pass.
AO-7 is in the Pro list — why does it have special notes?
AO-7 is a special case — it's been in orbit since 1974 and its batteries failed long ago. It operates only when in sunlight (Mode B: 145.850 uplink, 29.4 MHz downlink). Passes in eclipse will produce no signal. The operating notes on the pass card flag this.
Still Have a Question?
If your question isn't answered here, send it via the feedback form. I read every message and update this FAQ based on common questions.
73 de VE3AKK