Feld Hellschreiber vs Odmaster
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Feld Hellschreiber
This app decodes and transmits text messages using the historical Hellschreiber system, which sends characters as audio signals. It's ideal for amateur radio operators and enthusiasts interested in vintage communication methods. The app allows for both manual text entry and pre-set messages, with adjustable display contrast for optimal viewing.
- Decode Hellschreiber messages
- Transmit text messages
- Canned text message support
- Adjustable display contrast
- Real-time text scrolling
- Audio input/output via device mic/speaker
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Hellschreiber is a teleprinter system, developed in the 1920s, that transmits text via sound, much like an old facsimile (fax) system. Each pixel of a character is transmitted as a short burst of audio. It works even under very noisy and poor reception conditions, because your brain does the work of analyzing the received image to pick out the characters. It was used by the German military during World War II to send messages encrypted by ENIGMA machines. Today it is used by amateur (ham) radio operators around the world to send messages to each other via shortwave radio. Feld Hellschreiber literally means "bright field recorder". Hellschreiber is sometimes referred to as simply Hell. Feld Hellschreiber lets you decode and transmit Feld Hell messages. Decoded text is continuously scrolled across the top of the display. You can type in text to transmit, or press a button to easily send canned text messages, such as CQ calls. Sound is picked up from your radio's speaker via the internal mic in your device, and transmitted audio comes out the speaker - you can also connect a patch cable to your radio's mic input via the headphone jack on your device to transmit the audio, if you wish. The slider control adjusts the display contrast, and the indicator to the right shows the volume. Adjust the slider for the best display. To transmit text, touch on the text entry field, and start typing. Each character will be sent when possible. When sent, it will be taken off the left end of this field, and displayed on the right end of the transmitted text field, to the left of the entry field, in a scrolling fashion. Canned text buttons are also available, touch one to send the text stored for that button. To edit a button, touch the Setup button, and then select the button you wish to edit. You can edit the name of the button, as well as the text. To decode transmissions, you just need to run the app, and set it near the radio's speaker or headphones, and watch the decoded text appear. It's that easy!
Odmaster
This application allows users to program various radio models directly from their mobile phones, eliminating the need for a computer. It offers a convenient and portable solution for radio programming and includes a community feature for sharing content and interacting with other users.
- Program radio with mobile phone
- Supports multiple radio models
- Convenient and portable programming
- Community sharing and interaction
- Help Center and direct support
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• Use Odmaster to program your radio faster and easier. Multiple radio models are set in the application. At the same time, you can share interesting content on the community page. Bring you a different experience! • • Program radio • (Tips:this function requires a Bluetooth programmer device) • • Program radio with mobile phone instead of computer easily • • Program radio conveniently, anytime and anywhere • • Program multiple models of radios • • Remote programming radio when you don’t know how to program • • Social function • • Can post something interesting on it • • Give someone a like • • Make comments on others posts • • Help&Support • • If you have any problems during using App, you can find the answers in Help Center, or contact us. • • ► Get some programming information in our YouTube website: • https://www.youtube.com/channel/UCW5VMOpgmTdUQq5ZqyIL2hA/videos • ► Contact detail: E-mail: odmaster@tid-china.com • ► Online manual:https://bit.ly/tidmanual
Screenshots
Verdict
The clearest difference is review sentiment: Feld Hellschreiber at 75% against Odmaster's 29%. Feld Hellschreiber also leads on iOS requirement (6.0 vs 14.0). Odmaster's advantage is price (Free vs $2.99) and rating (3.8 vs 2.8). On ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Odmaster is free to download; Feld Hellschreiber costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Odmaster holds the better App Store score, 3.8 against 2.8. That said, the two scores are not equally well evidenced: Odmaster has 1.1K ratings behind it against 5, so its average is the more settled of the two. Written reviews complicate that: 75% of Feld Hellschreiber's written reviews are positive against 29% of Odmaster's, so the app with the better star average is not the one people write more warmly about.
Feld Hellschreiber ships an update every 13 months, Odmaster every 3 weeks. The most recent releases landed on September 20, 2026 and October 6, 2026 respectively.
| Parameter | Feld Hellschreiber | Odmaster |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | 2.8 (5 ratings) | 3.8 (1.1K ratings) — better |
| Positive reviews | 75.0% of reviews — better | 29.1% of reviews |
| Number of ratings | 5 | 1.1K — better |
| Update frequency | Every 13 months | Every 3 weeks — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 6.0 — better | 14.0 |
| Further details — not scored | ||
| Size | 4 MB | 96 MB |
| Age rating | 4+ | 17+ |
| Developer | Black Cat Systems | Guangzhou Billion Leiden Electronic Technology Co., Ltd. |
Customer experience
Feld Hellschreiber
Odmaster
Bugs and requests
Feld Hellschreiber
Not enough reviews yet to summarise bugs or requests.
Odmaster
Reported bugs
3 issues- Unable to read or write radio data
- Inconsistent behavior across iOS versions
- Login and account issues
Requested features
3 requests- Support for more radio models
- Ability to save and load custom channel configurations
- Improved user interface and navigation
In-app purchases
Feld Hellschreiber
No in-app purchases
Odmaster
No in-app purchases









