# GPS Diagnostic: Satellite Test — Precise Coordinates & Altitude

> iPhone/iPad GPS diagnostic tool with precise coordinates and altitude. (iPhone/iPad app by David Ryall.)

- Source: https://appshunter.io/ios/app/gps-diagnostic-satellite-test/id1020967894 (this page in markdown: same URL + `.md`)
- Developer: [David Ryall](https://appshunter.io/developer/925576172)
- Category: Navigation, Utilities
- Price: $2.99 with in-app purchases
- Rating: 4.70/5 from 546 App Store ratings · 209 written reviews indexed
- Age rating: 4+
- Requires: iOS 8.0 · 34 MB
- Languages: American English, Greek, Japanese, Korean, Russian, Chinese (Simplified, China), Chinese (Traditional, Taiwan), Vietnamese
- Released: 2015-09-10
- Data updated: 2026-08-25
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/gps-diagnostic-satellite-test/id1020967894/reviews.md

## What is GPS Diagnostic?

KEY FEATURES:

- Essential tool for your iPhone & iPad.
- Test the GPS module.
- Fast GPS lock time.
- Precise navigation parameters.
- Supplements operation of your navigation apps.
- GPS "JumpStart" technology.
- If location cannot be determined then it diagnoses why.
- Assists you in changing conditions to get a reliable location.
- GPS, Galileo, GLONASS, QZSS full support.
- Latitude & Longitude, and WGS84 included by default.
- In-App Purchase: USNG, MGRS, UTM, OSNG, GEOREF, GARS & 174 Datums (free basic functionality).
- **NEW** Smaller footprint (now only 35MBytes)
- Free technical and customer support by email.

--------------------------------------
OVERVIEW:

- Lodestone Chart™ displays all essential GPS satellite information using a chart with only 4 bars. This dramatically simplifies the diagnostic process (Registered Copyright).

- GPS "JumpStart" technology may resolve GPS problems with third-party navigation applications that have a frozen location, are slow to respond or are performing inaccurately.

- Uses the internal GPS of your iPhone or iPad.

- Includes a Speedometer, Altimeter and Compass.

- Location and altitude ( best-in-class accuracy and reliability )

- Speed (SOG) and Course (COG).

- Heading (i.e. Compass) with ability to turn on and off the manual compass calibration.

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IN-APP PURCHASE (IAP)  = "COORDINATES-PRO"  

This adds additional coordinate systems and datums to the app to let you accurately work with many paper maps and charts used by civilians, U.S. military and NATO forces for walking, sailing, and flying. The coordinate systems and datums included are:

- United States National Grid (USNG)
- Military Grid Reference System (MGRS) -Old and New
- Universal Transverse Mercator (UTM)
- Ordnance Survey National Grid (OSNG) for Great Britain
- World Geographic Reference System (GEOREF)
- Global Area Reference System (GARS)

- 174 Datums (e.g. WGS84, NAD83, NAD27, WGS72, ED50, ED79,  OSGB36 etc....).
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REVIEWS: 

- The developer is a professional software and hardware engineer working in the satellite space industry. He is a yachtmaster and pilot with a passion for navigation and Apple products.

- Consistent 5 star reviews, see what users are saying:

"Perfect Diagnostic Tool - This is the best app if you need to know the actual status of the internal GPS."
"Great app for kick starting navigation apps - This app finds a position every time and then all other nav apps work."
"Excellent application - This was a much needed application for iOS devices."
“I love the app. It’s been great to have when buying a new phone from eBay to check that the GPS is working. I had to return 3 phones last time before I got one with operational GPS.”
"Awesome, over used term but this app is - This app does what other developers said they could not do."
--------------------------------------
MORE INFORMATION:

- Hardware information

- Accuracy of measurements shown for pro users.

- Imperial, metric and nautical units. These are the most commonly used and most useful navigation units. All easily changeable from the screen in use.

- Does not require internet access and does not use cellular data.

- Essential tool for any power user.
    (e.g. navigators, yachtsmen, pilots, app developers)

- Share your location by text message, email etc. The format contains all essential information for improved accuracy.

- Works with Garmin Glo.

- GPS Diagnostic™ is a professional GPS test and measurement utility for your iPhone and iPad.

## Key features

- Test GPS module
- Fast GPS lock time
- Precise navigation parameters
- GPS "JumpStart" technology
- Full satellite system support
- Additional coordinate systems (IAP)

## Pricing and in-app purchases

Base price: $2.99.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Coordinates-Pro | Free | one-time |


## Chart rankings

- #60 in Top Paid · Navigation (US App Store)

## What do users think of GPS Diagnostic?

Overall sentiment: positive

**Pros**

- 👍 Helpful diagnostic tool
- 🚀 Provides detailed GPS information
- 🔧 Useful for troubleshooting GPS issues
- 💡 Allows resetting GPS receiver
- 👍 Clean and intuitive interface
- 🔍 Accurate GPS data

**Cons**

- 🐛 Compatibility issues with newer iOS versions
- 🔍 Limited satellite data display (only 4 bars)
- 📝 Email support button not working
- 🔍 Lacks detailed information on satellite types

**Commonly reported bugs**

- Crashes on startup for some users
- Fails to detect GPS signal on certain devices

**Most requested features**

- Display number of satellites in view and locked
- Expand satellite signal strength graph to show more satellites
- Add support for landscape mode
- Provide more detailed GPS information (e.g., HDOP, VDOP)

## Recent user reviews (10 of 209)

All indexed reviews: https://appshunter.io/ios/app/gps-diagnostic-satellite-test/id1020967894/reviews.md

### 5/5 — Perfect Partner to iNavX

*2026-06-20*

Just got a new-to-me iPad to use iNavX at a better size than my phone. Panicked when that and map apps, barometer nor any gps apps were working. Read the reviews, downloaded this to find that this little old(er) tablet needs a clearer view of the sky to find satellites than my iPhone does. iNavX is happy now - I am where it thinks I am. Still gonna keep this open right beside the nav app because I can see what this is doing. Excellent app - Thank You!

### 5/5 — Very Useful Utility

*2026-04-12, version 3.6*

I’ve been using GPS Diagnostic for years. Very useful, especially for an accurate speedometer.  Thanks!

### 1/5 — Poor documentation and support

*2026-01-16, version 3.6*

The documentation is just screenshots that explain the blindingly obvious with no necessary detail. The email support button cannot find the email app on my iPhone. Manually emailing the developer is ignored. So, when it gives you baffling responses (like a question mark next to GPS installed hardware) you are on your own trying to work out what that means. It’s not a lot of money - but it is wasted.

### 4/5 — Diagnostic Window

*2026-01-15, version 3.6*

Diagnostic window  only shows wifi compass and bluetooth with a green tick. cellular is blank and Gps shows a ? Any ideas as to why this is so.

### 5/5 — SEE WHAT SATELLITES YOU HAVE CONNECTED

*2025-12-01, version 3.6*

This is great for trouble shooting your gos on your phone

### 1/5 — 垃圾

*2025-09-27*

诊断页 GPS 和蜂窝都无显示，且测试卫星信号强度与实际不符。这玩意是逗我玩的吧

### 5/5 — Excelente

*2025-08-08*

Todas as funções liberadas com o pagamento único da compra. Informação certa e completa, sem frescuras.

### 2/5 — updates??

*2025-07-14*

GPS Modul Iphone 16 not more recognized. No Support for actuel IOS Version !

### 1/5 — .

*2025-05-24*

Доброе времени .для iOS 18.5 актуально?

### 5/5 — Good communication

*2025-04-29, version 3.6*

Got the app and had a question.  Emailed David and he responded immediately to help me figure out my GPS issue.

## Frequently asked questions about GPS Diagnostic

### What does the GPS Diagnostic: Satellite Test app do?

This app is designed to test your iPhone or iPad's GPS module, providing precise navigation parameters like latitude, longitude, altitude, speed, and course. It also helps diagnose why location cannot be determined and assists in achieving a reliable location under changing conditions.

### What are the key features of this GPS app?

Key features include testing the GPS module, fast GPS lock times, precise navigation parameters, and GPS "JumpStart" technology to resolve issues with third-party navigation apps. It fully supports GPS, Galileo, GLONASS, and QZSS satellite systems, and includes a speedometer, altimeter, and compass.

### Is the app free to use?

The app offers free basic functionality, including essential GPS diagnostics and standard coordinate systems like Latitude & Longitude. Advanced features, such as additional coordinate systems like USNG, MGRS, and UTM, along with 174 different datums, are available through an in-app purchase called "COORDINATES-PRO".

### What devices is this app compatible with?

The app is an essential tool for your iPhone and iPad. It utilizes the internal GPS of these Apple devices to provide its diagnostic and navigation functionalities.

### How can this app help with navigation or checking a new phone?

This app can help kick-start navigation apps by ensuring a reliable GPS fix. Users have found it useful for checking if the GPS is operational on a new phone, especially when purchasing used devices, to avoid returning multiple units with faulty GPS.

## Version history (last 5 releases)

### 3.6 — 2020-06-25

80% reduction in file size to 35MB. Full support for latest iPad Pro 4th Generation.

### 3.5 — 2020-05-17

Universal Transverse Mercator (UTM) coordinate system added.

### 3.4 — 2020-05-04

User display improvements. Support for iPhone SE2 and older iPhones and iPads running iOS8 and iOS9.

### 3.3 — 2019-12-09

Update to support latest iPhones and iPads: iPhone 11 / 11 Pro / 11 Pro Max and iPad mini 5th Gen/iPad 9.7 inch 7th Gen/iPad Air 3rd Gen.

### 3.2 — 2019-02-04

Support for iPhone XS, XS Max, XR and latest iPad versions.

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## More apps by David Ryall

- [Compass Guru - Digital Heading & Bearing](https://appshunter.io/ios/app/compass-guru-digital-heading-and-bearing/id1161588289)

All apps by David Ryall: https://appshunter.io/developer/925576172

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-25.*