Voice vs Asynchronous Data for Survival Radio and Prepping

Someone asked if either Voice or Data were better for prepper comms. My answer could surprise you.
This post is an addendum to the video Voice versus Data Modes Off Grid Ham Radio & Prepping.

With so many questions about voice modes versus data modes for survival radio and prepping, I decided to make a short video. We already know my opinion on asynchronous data and messaging (truly no-brainers). Still, it may be a good to add some context.

Real-time comms

Voice modes are fine when everyone is in the right place, at the right time, and on the correct frequency. Security guards in a shopping mall use voice comms in real-time to coordinate their movements. Truckers use real-time voice comms to warn each other of traffic hazards along the highway. Survival and preparedness groups also use real-time voice comms to coordinate their movements, share information, … As long as everyone is where they should be, when they should be there, and on the right frequency, voice modes work fine! However, if any chaos is introduced, our real-time comms plan begins to fall apart rather quickly. Even if we have a contingency plan, choas has a nasty way of getting everyone out of sync.

Real-time modes like Voice, CW, RTTY, PSK, MFSK, … are great when everyone is on the same page, at the same time. Real-time comms is excellent for random contacts and scheduled contacts. When you’re trying to get in touch with a specific person, at a specific time, but one or the other is late or delayed somehow, the dominos begin to fall. Adding interferance on the frequency or band makes completing the QSO that much more difficult.


Real-time comms are dependant upon schedules, clear channels, and correct frequency. Remove any one of these dependencies, are our real-time comms will fail! If we are not on-air at the correct time, and at the correct frequency, there can be no real-time communications. Yes, but the backup plan Julian! True, a fallback comms plan is usually decided upon. Unfortunately, we often make the mistake of implementing a fallback plan which has the same failure points as our primary real-time comms plan. If we can’t reach each other on this frequency, then go to that frequency and so on. Our contingency plan is weak at best!


One of the workarounds for the voice mode points of failure is ALE. Automatic Link Establishment (ALE) provides HF radios the ability to automatically link using the best frequency. ALE stations scan a set of channelized frequencies. These frequencies can span a single band, multiple bands, or across HF, VHF and UHF. If one channel is occupied, ALE will continue scanning for a clear frequency, with the best chances of reaching the station you’d like to eastablish a call (aka QSO) with. Think of it as the operator of a switchboard. It will find a stable and reliable path to the station you want to QSO with. It will then alert that station of the incoming voice call. We will discuss this in more detail on the channel later this year.

Asynchronous data & Messaging

Asynchronous messaging works in parallel with our real-time comms plan. If we are talking about JS8Call, Winlink or VarAC, many stations operating on various bands and frequencies, providing multiple entryways to get messages through. When our attempts at using our primary comms (voice) fails, asynchronous messaging can become our fallback.

With asynchronous messaging, we can put out a message onto the network for the recipient to collect “when it is possible”. We are not dependent upon being on the same frequency, at the same time as with real-time comms like voice or CW.

With voice comms, If we were not able to hear a voice call coming in, the QSO cannot take place. In contrast, an asynchronous message will be waiting on the network, whether or not you can hear the sending station directly. See where we are going here?

As a fallback solution, that asynchronous message could be instructions for getting back in touch on a real-time mode, at a specific time and frequency for example. It could also be a message with instructions about which way you are heading. This helps with the organising a rendezvous on air, or in person. When we use asynchronous messaging, the messages can be stored on stations far outside the disaster area, but well within your HF comms reach. This discussion begins to show some of the differences between V/UHF and HF. It is interesting, but let’s leave that for another day.

So the answer is:
Voice and asynchronous data are incredibly important. They compliment one another in ways neither could accommodate on their own. For this reason, we need to plan for and train with both! If you have not watched the video yet, here it is. It is short format, with no fluff.

Please share the video or blog:
Blog url: https://oh8stn.org/blog/2023/01/17/voice-vs-asynchronous-data-for-survival-radio-and-prepping/
Video url: https://youtu.be/rCm7IbyjRxg

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