Legal in Germany

Hi there,
I am concidering to buy the TTGO T-Beam in the 433mHz Edition, but i did a little research and found that the only availible Frequenz in Germany is the 433 but can i use It without legal concerns? I have heard that the so called “Jedermannfunk” devices need a special aprooval.


Sorry - no idea. Hopefully someone who knows broadcaster regulations/testing requirements in Germany will speak up. We try to use the LORA frequencies & power levels that are ‘supposed’ to be legal in various regions, but we certainly haven’t carefully verified this.

When I was initially putting together the 433 range, I was referring to the LoRa TTN documentation for what they use, as they seem to follow local regulations.

From there, they link to specific regulations for different countries. There’s a PDF here, in German so I’m just looking at the frequencies and ERP, but it looks like you’re okay to use the EU 433 Meshtastic build in Germany.

I have looked that up too but I am only allowed to brodcast with up to 10 mw ist that implemented in the code? In the law it says that only by the gouverment aproved hardware can be used in order to use theese fequencies.

Ps. I’ve send a e-mail to the corresponding authority.

Let us know what you hear - will be good to have it documented.

Sure, I think in Europe its pretty much the same as in Germany !

10mw I think is also 10dbm, convenient , in MeshRadio.cpp: channelSettings.tx_power = 23; you can change that to 10? Maybe look at the rfm95 library to confirm the units.

I’ve been looking at the UK laws. I wanted to get 433Mhz because my original plan was to have two private nodes communicating for a remote sensor over about half mile. I knew that LoRaWAN mainly used 868Mhz in UK, I thought 433Mhz may be less busy, well apart from my neighbours door bells, garage openers, car fobs etc. It seems that although 433Mhz has lower power rules the duty cycle is higher, so you can lower bandwidth and increase spreadcycle to obtain better reach. The documents are confusing and seemingly contradicting, so if you find one that you can fit into your criteria and say you are working from that if anyone asks eg: I found one that had different dbm limits for downlink and uplink, for a mesh radio like this you can call which ever node you want the up/down link

No in fact it is limeted to 10 mW.

Duty cycle 10% though. Thats an advantage, using the default settings with the ttgo sample sketch i got about 200meter range, dropping the bandwidth and going to spreadcycle 12 i was getting about 90% packets all over my small town even with no line of sight. Data rate is slow but that doesn’t matter too much unless you need long battery life.

for whatever it’s worth 23 dbm is what the (carefully tested and reviewed) folks use in Europe (with essentially the same hardware) - so I presume there is a similar rule these devices fall under.

yes, spread factor 12 is what we use by default (and real soon now - I’m working on the UI currently - people will be able to change it)

That would be cool to change it at user level, bandwidth, coding rate, spreading factor and tx power. after all its a private mesh and different applications can prioritise speed/range/battery life.
I was using bandwidth 31k SF 10 Coding rate 6, txpower 20 and I got good range with that, I got bad range with the defaults which are 125k, SF7, CR 5, tx Power 17. There’s a data rate calculator Here ( my settings are 122bps

I agree!

Here’s the settings the radio currently supports changing. I’m working on a nice UI in the android app now for letting the user customize for their channel:


// Full settings (center freq, spread factor, pre-shared secret key etc...) needed to configure a radio for speaking on a particlar channel
// This information can be encoded as a QRcode/url so that other users can configure their radio to join the same channel.
message ChannelSettings {
    int32 tx_power = 1;

    // We now select channel number by hashing the name of the channel.  We do this on the device and it is opaque
    // to the phone.  Therefore no need to show this in channel settings
    // uint32 channel_num = 2;

    enum ModemConfig {
        // Note: these mappings must match ModemConfigChoice in the device code.
        Bw125Cr45Sf128 = 0; ///< Bw = 125 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Default medium range
        Bw500Cr45Sf128 = 1; ///< Bw = 500 kHz, Cr = 4/5, Sf = 128chips/symbol, CRC on. Fast+short range
        Bw31_25Cr48Sf512 = 2; ///< Bw = 31.25 kHz, Cr = 4/8, Sf = 512chips/symbol, CRC on. Slow+long range
        Bw125Cr48Sf4096 = 3; ///< Bw = 125 kHz, Cr = 4/8, Sf = 4096chips/symbol, CRC on. Slow+long range

    /// This value replaces bandwidth/spread_factor/coding_rate.  If you'd like to experiment with other options
    /// add them to MeshRadio.cpp in the device code.
    ModemConfig modem_config = 3;
    // uint32 bandwidth = 5;
    // int32 spread_factor = 6;
    // int32 coding_rate = 7;

    /// A simple preshared key for now for crypto.  At first I'm using 128 bit (16 byte) block for the Speck crypto
    /// but for beta we'll want something more carefully thought through.  I want to keep the QR code small
    bytes psk = 4;

    /// A SHORT name that will be packed into the URL.  Less than 12 bytes.  Something for end users to call the channel
    string name = 5;

ok I got answer, they send me only the document mentioned before, Is anybody else german in this forum and can help me?

Alas, sorry I don’t know. Hopefully someone will speak up. Out of curiosity your question led me to check the android app usage stats. Supposedly (not sure how accurate), there are 32 users in Germany. Though I think the %s that check this forum are probably low.

Hi have you enforced a 10% duty cycle somehere in the code?

AFAIK the best option for UK/EU is 869.4-869.65 MHz with enforced 10% Duty cycle and 500mW.

From page 11 of this document:

To be properly legal I think you would also need a CE marked board.

Nope, no enforcement yet (and not for 1.0). But someday!

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OK, thanks. AFAIK it’s a requirement for legal use anywhere in Europe or UK.