Comparison

Feld Hellschreiber vs On

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Decode Hellschreiber messages
  • Transmit text messages
  • Canned text message support
  • Adjustable display contrast
  • Real-time text scrolling
  • Audio input/output via device mic/speaker
Features
Read full description

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!

About

On

This tool assists amateur radio operators with managing on-air nets and check-ins. It offers real-time messaging, email integration, and detailed operator information retrieval. The app supports multiple simultaneous sessions and configurable displays for efficient communication and tracking.

Highlights
  • Real-time net check-in tracking
  • Instant messaging (AIM) sessions
  • Integrated email client
  • Configurable information displays
  • QRZ/QRZCQ call sign lookup
  • WebSDR audio streaming
  • QRZ Logbook integration
Read full description

On-Air Net Scraper "Personal" Pro is an iPhone/iPad/MacOS silicon App providing a wide range of features for Amateur Radio operators (Hams). Key features include NetLogger Amateur Radio On-Air Nets, Check-Ins and multiple Almost Instant Message (AIM) sessions in real-time data awareness. AIM pass key automatic email request with single button click resulting in immediate pass key information reply. Full integrated Email client for yet another method for Hams to carry out conversations. Multiple tabbed displays allowing user to track unlimited number of On-Air Net Check-Ins at one time. User configurable information displays to included viewing detailed Ham information within Check-In views. Near real-time AIM client text message send and receive. Searching and viewing Past NetLogger Nets and Check-Ins. Monitor mode so users can be aware of NetLogger Check-In "lurkers". Simultaneous QRZ and QRZCQ login is supported facilitating Call Sign lookup and Ham information retrieval. Easy, click to display NetLogger Nets, Check-Ins Call Sign and operator status information, not requiring QRZ/CQ accounts. Multi-screen displays to included improved 2-way and 3-way split screens provide simultaneous displays of Check-Ins, AIM, AIM and Net Scraper Message Exchange current listing data along with WebSDR viewing and listening. PERSISTENT WebSDR radio LIVE audio listenings while simultaneously viewing multiple Net Check-In views. Seamlessly integrates with On-Air Net Scraper Desktop Server WebSocket Interface supporting private Internet chat sessions between On-Air Net Scraper ME clients. JS8Call/WSJTX full participation in digital radio REAL-TIME texting when using NetBird VPN or when paired with On-Air Net Scraper's Message Exchange (ME) Server. Autoload favorite NetLogger nets. Callsign search both NetLogger Active and Past net listing, including improved automatic continuous search and displaying of matched nets. QRZ Logbook insert/update/delete. Supports On-Device authentication and Two-Factor authentication in addition to encrypted secure storage of sensitive data and app access security. JS8Call dynamic frequency adjustment.

Screenshots

Feld Hellschreiber1 screens
On4 screens

Verdict

The call

The clearest difference is price: On at Free against Feld Hellschreiber's $2.99. On also leads on rating (4.4 vs 2.8) and update cadence (monthly vs every 13 months). Feld Hellschreiber's advantage is review sentiment (75% vs 50%) and iOS requirement (6.0 vs 15.6). On ratings volume, 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

CostPrice · In-app purchases · Ads · Monetization

On is free to download; Feld Hellschreiber costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

On holds the better App Store score, 4.4 against 2.8. Both are backed by a comparable volume of ratings — 5 and 13 respectively. Written reviews complicate that: 75% of Feld Hellschreiber's written reviews are positive against 50% of On's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

Feld Hellschreiber ships an update every 13 months, On monthly. The most recent releases landed on October 8, 2026 and October 15, 2026 respectively.

Scorecard6 real differences · 4 level
Feld Hellschreiber versus On: the parameters behind the verdict, then further details
ParameterFeld HellschreiberOn
Price$2.99Free — better
Rating2.8 (5 ratings)4.4 (13 ratings) — better
Positive reviews75.0% of reviews — better50.0% of reviews
Number of ratings513 — better
Update frequencyEvery 13 monthsMonthly — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod, Mac — better
Requires iOS6.0 — better15.6
Further details — not scored
Size4 MB30 MB
Age rating4+17+
DeveloperBlack Cat SystemsChristopher Robson

Customer experience

Feld Hellschreiber

All ratings5 ratings
Positive40.0%
Neutral0.0%
Negative60.0%
Written reviews16 reviews
Positive75.0%
Neutral12.5%
Negative12.5%

On

All ratings13 ratings
Positive84.6%
Neutral7.7%
Negative7.7%
Written reviews8 reviews
Positive50.0%
Neutral12.5%
Negative37.5%

In-app purchases

None

Feld Hellschreiber

No in-app purchases

None

On

No in-app purchases

Questions

Is Feld Hellschreiber free?
Feld Hellschreiber costs $2.99, with no in-app purchases.
Is On free?
On is free to download, with no in-app purchases.
Which has better reviews, Feld Hellschreiber or On?
On is rated higher. Feld Hellschreiber averages 2.8 out of 5 from 5 ratings, while On averages 4.4 from 13 ratings.
Do Feld Hellschreiber or On have ads?
Neither Feld Hellschreiber nor On shows ads.
Which is updated more often, Feld Hellschreiber or On?
Feld Hellschreiber ships an update every 13 months, and On monthly. Most recently, Feld Hellschreiber was updated on October 8, 2026 and On on October 15, 2026.

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