Comparison

Feld Hellschreiber vs ST

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

ST

This app converts photos and images into a format compatible with D-STAR transceivers for the Share Picture function. Users can crop images, add text like call signs, and transfer them wirelessly or via Bluetooth to supported transceivers.

Highlights
  • Image conversion for D-STAR Share Picture
  • Image cropping
  • Add text (call signs)
  • Wireless transfer to transceiver
  • Bluetooth transfer to transceiver
  • Save cropped image as file
Features
Read full description

The ST-4001I is an application to crop an image used for the Share Picture function of a D-STAR transceiver, and transfers it to the transceiver. ・Photos taken, or photos/images saved on the iPhone and iPad can be converted into the format used for the Share Picture function of the D-STAR transceiver. ・You can crop the image and enter text such as a call sign. ・The cropped image can be transferred through a network to the D-STAR transceiver. ・The cropped image can be transferred through a network or using Bluetooth to the D-STAR transceiver. ・You can also save the cropped image as a file. Refer to the INSTRUCTIONS for details. Device requirements: iOS12 or later Supported transceiver (As of July 2024) Transceivers that can transfer via Bluetooth Icom ID-52A/E Icom ID-52A/E PLUS Transceivers that can transfer via network Icom IC-705 Icom IC-905 Icom IC-9700* *Firmware version 1.20 or higher NOTE • Icom does not guarantee that the ST-4001I works on all iPhone and iPad. It may not work properly, depending on the OS version, installed applications, or other reasons. • The transceiver and iPhone and iPad must be connected to the same network to transfer an image to a transceiver through a network. • Bluetooth LE is used to connect to a transceiver using Bluetooth. Transferring an image may take some time due to a slow data transfer rate.

Screenshots

Feld Hellschreiber1 screens
ST4 screens

Verdict

The call

The clearest difference is price: ST at Free against Feld Hellschreiber's $2.99. ST also leads on rating (5.0 vs 2.8). Feld Hellschreiber's advantage is review sentiment (75% vs 50%) and update cadence (every 13 months vs every 27 months). 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

ST 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

ST holds the better App Store score, 5.0 against 2.8. Both are backed by a comparable volume of ratings — 5 and 2 respectively. Written reviews complicate that: 75% of Feld Hellschreiber's written reviews are positive against 50% of ST'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, ST every 27 months. The most recent releases landed on October 8, 2026 and October 9, 2026 respectively.

Scorecard6 real differences · 4 level
Feld Hellschreiber versus ST: the parameters behind the verdict, then further details
ParameterFeld HellschreiberST
Price$2.99Free — better
Rating2.8 (5 ratings)5.0 (2 ratings) — better
Positive reviews75.0% of reviews — better50.0% of reviews
Number of ratings5 — better2
Update frequencyEvery 13 months — betterEvery 27 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS6.0 — better12.0
Further details — not scored
Size4 MB12 MB
Age rating4+4+
DeveloperBlack Cat SystemsICOM INCORPORATED

Customer experience

Feld Hellschreiber

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

ST

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

In-app purchases

None

Feld Hellschreiber

No in-app purchases

None

ST

No in-app purchases

Questions

Is Feld Hellschreiber free?
Feld Hellschreiber costs $2.99, with no in-app purchases.
Is ST free?
ST is free to download, with no in-app purchases.
Which has better reviews, Feld Hellschreiber or ST?
ST is rated higher. Feld Hellschreiber averages 2.8 out of 5 from 5 ratings, while ST averages 5.0 from 2 ratings.
Do Feld Hellschreiber or ST have ads?
Neither Feld Hellschreiber nor ST shows ads.
Which is updated more often, Feld Hellschreiber or ST?
Feld Hellschreiber ships an update every 13 months, and ST every 27 months. Most recently, Feld Hellschreiber was updated on October 8, 2026 and ST on October 9, 2026.

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