Description

NPR (New Packet Radio) is a custom radio protocol, designed to transport bidirectional IP trafic over 430MHz radio links (ham radio frequencies 420-450MHz). This protocol is optimized for "point to multipoint" topology, with the help of managed-TDMA.
Bitrate is 50 to 500kbps (net, effective bitrate), depending on the RF bandwidth chosen.
The radio modem is cheap (~80$) and home-made, with a 433MHz ISM module inside (flexible enough to be tuned over the whole 420-450MHz band). The modem is connected locally with Ethernet, therefore no specific software is needed on PC.
The modem is easy to build and reproduce.
You can add a DMR radio amplifier in order to achieve 20W radio power or more.
The main usage is an extension of HSMM - Hamnet - AREDN networks.
All the project is open-source : hardware, software, protocol specification.

Details

NPR modems FOR SALE: https://www.elekitsorparts.com/product/npr-70

Low prices (79$ fully assembled). International shipping.

Note for USA: Due to CFR 47 Part 97 FCC regulations, for the 70cm amateur radio band (restriction to 100kHz and 56kBaud), only the setting "modulation 20" of NPR-70 seems to be legal in USA. Please always check your local amateur-radio regulation before buying and using NPR70.
Modulation 20: Symbol Rate 50kS/s, bandwidth 100kHz, raw datarate 100kb/s raw, usable datarate 65kb/s.

If you want to discuss about NPR:

via e-mail : f4hdk[at]free[dot]fr
Public discussion English : the public chat room
Public discussion French : Electrolab forum
Mailing list (mainly USA) : groups.io
Mailing list (mainly Europe) : groups.io

watch full screen.

Documentation

Introduction and quick start guide v3.6 English	Introduction et guide de démarrage rapide v3.6 Français
Advanced user guide (EN & FR) v2.16
Modem assembly and programing guide (EN & FR)
Spectrum Occupancy
NPR protocol Specification (EN)

PCB Design (Gerbers, BOM, etc...)

PCB v02	BOM Easy to provision Total cost ~80 euros per modem	BOM (Bill Of Materials)	PCB files	release note
PCB v03	Cheaper BOM Total cost ~65 euros per modem	BOM (Bill Of Materials)	PCB files	release note
PCB v04	Old version sold by Funtronics. Obsolete do not use.	-	PCB files	release note
Add-on SRAM board	for PCB v04 only	-	PCB files	release note
PCB v05	New version for Funtronics. Fits Funtronics enclosure	BOM (Bill Of Materials)	PCB files	release note

Modem Firmware : binaries and sources

Stable version 2020_02_23	Beta version 2020_06_29
Binary file, band 70cm	Binary file, band 70cm
Binary file, band 2m	Binary file, band 2m
Release note	Release note
Source code	Source code

Files

NPR_advanced_guide_v2.16.pdf

Adobe Portable Document Format - 2.08 MB - 11/27/2021 at 10:30

Preview

NPR70_introduction_FR_v3.6.pdf

Adobe Portable Document Format - 1.66 MB - 06/29/2020 at 10:00

Preview

NPR70_introduction_EN_v3.6.pdf

Adobe Portable Document Format - 1.66 MB - 06/29/2020 at 10:00

Preview

NPR_FW_source_2020_06_29.zip

x-zip-compressed - 5.29 MB - 06/29/2020 at 09:39

Download

NPR_FW_2020_06_29_band70cm.bin

octet-stream - 176.08 kB - 06/29/2020 at 09:39

Download

Project Logs

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6- Last news, updates
f4hdk • 10/20/2019 at 14:59 • 0 comments
27 Nov 2021
I have modified the "advanced user guide". The "command list" table inside annex Annex-1 was totally messed up; now it is ok. Sorry for that.
29th June 2020:
- Important firmware update about Ethenet mode configuration 10Mb/s or 100Mb/s, half or full duplex; it can solve a recurrent problem of packet loss and low datarate. Refer to the new version of the "advanced user guide". Many thanks to Kevin M0AHN who discovered the origin of the problem.
- Inside Advanced user guide : New recommendation added about daily reboot for modems which are ON 24H/day.
23rd Feb 2020:
- New firmware with new features
  - The modem can now drive an external PA with its GPIO port
  - In case of SPI SRAM present (auto detected), the TX data buffer is increased to 128kB instead of 16kB previously. Big improvement of the quality of IP connection.
  - Radio connection establishment time greatly reduced.
  - TX_test feature finally debugged and stable.
- Documentation updated ("Advanced user guide" and "Assembly and programming guide") mainly about SPI-SRAM, about PTT ouptut, and about firmware upgrade.
- Important info about SPI-SRAM :
  The RAM of the microcontroller used is too limited to have good performances, especially at Master side.
20th Jan 2020:
- Advanced user guide updated, mainly in order to clarify IP config of modems (client modems). Refer to revision history.
- Important info: The solution 1 for upgrading the RAM (see below) is feasible, with external SPI SRAM. I will provide soon (february) cheap add-on SRAM boards, and a new firmware (compatible with and without this SPI-SRAM). For modems v04 only. v02 and v03 already have the SPI-SRAM, and the future version v05 will have it also.
1st Jan 2020:
- Documentation updated (advanced user guide and introduction) : command "TX_test", adding a fan on the amplifier, setting the MTU to 750 for better performances.
- Important info : for future features, especially for the Masters, and for improving performances (buffer size), the RAM of the microcontroller is not big enough (64kB). I have 3 options, not decided yet, currently the 3 are under test:
  - Solution 1 (prefered): use the existing SPI-SRAM (23LC1024) of PCB v02 or v03. For PCB v04, I could provide a (very) cheap add-on board, easy to solder on top of the Nucleo. It's a shame that I removed this chip inside v04, I'm very sorry, I thought is was useless...
  - Solution 2: use an external SPI-SRAM in QSPI configuration. The existing PCBs (v02, v03, v04) are not compatible at all, new PCB needed.
  - Solution 3: use a brand new microcontroller (Nucleo L476RG), with a totally new PCB, larger.
8th Dec 2019:
- Document "advanced user guide" updated, refer to "revision history" inside.
26th Oct 2019:
- Modems are back for sale! Kits or assembled version. International sale. Low prices (79$ fully assembled). https://www.elekitsorparts.com/product/npr-70
- I have written an article on IEEE-Spectrum
20th Oct 2019:
- I have implemented the FDD (Frequency Division Duplex) feature, which is optional. You can now use separated frequencies for downlink and uplink (frequency shift), with one single modem at client side, and 2 modems and a RF duplexer at Master side...
Read more »
5- Planned or possible evolutions
f4hdk • 05/12/2019 at 06:26 • 0 comments
Please feel free to comment these lists of evolution, and express your requests, or your priorities. Either here or in the public chat.

Planned evolutions
- Better FEC algorithm, because currently it is very poor. If you can give me some help, I don't understand a lot standard FEC algo (with all these Maths).
- ~~Regular temperature check and re-calibration of SI4463 if necessary~~ -> done! (firmware 2019_06_16 and above)
- Increase to 15 clients instead of currently 7 maxi. → Probably not feasible with current hardware at Master side, not enough RAM (new hardware under study)
Possible evolutions, if people are interested (raw order, no priority order):
- ~~Static IP management of some modems~~ → Removed because you can use future "L2 pure ethernet transport feature" which will be more flexible
- Management via pure serial port (instead of USB)
- L2 Ethernet transport configuration (instead of currently L3 IPv4); could enable more flexibles topologies, and IPv6 compatibility. But a little bit less efficient.
- ~~Extension of frequency range to 420-450MHz instead of currently 430-440MHz (IARU region 1 limits)~~ -> done! (firmware 2019_06_16 and above)
- ~~Other modulation parameters, with lower datarates, in order to decrease RF bandwidth~~ -> Done (firmware 2019_06_16 and above)
- QoS necessary in order to transport VoIP data over an NPR network
- Totally new design, microcontroller with more RAM, PCB optimized for automatic PCB assembly line. Goal would be to mass produce fully assembled modems. Probability low, only if enough people are interested.-> Cancelled feb 2020. The current hardware is already "mass produced" by Funtronics - Elekitsorparts
- Frequencies split between uplink and downlink (in case you use NPR Master in a tower where a UHF FM repeater is already present). Additionally, the Master could be used in "FDD" (Frequency Division Duplex) mode in order to use these 2 frequencies simultaneously, like 2G or 3G mobile phones. 2 modems required at Master side. Complex! --> done! (20th oct 2019)
4- FOR SALE! (New Packet Radio modems).
f4hdk • 04/22/2019 at 06:34 • 0 comments

NPR modems for sale!
https://www.elekitsorparts.com/product/npr-70
Low prices (79$ fully assembled). International shipping.

If you want to sell kits from/to a particular region (either Europe or US or another), then I can add your contact e-mail and website inside this blog post.
3- Firmware history
f4hdk • 04/22/2019 at 06:21 • 0 comments

for later usage
2- Deployment, NPR networks, tests
f4hdk • 04/22/2019 at 06:20 • 1 comment

Tests by F4GOH:

https://twitter.com/f4goh/status/1126869444356186112

https://twitter.com/f4goh/status/1127252981278236672

https://twitter.com/f4goh/status/1127286377102684161

https://twitter.com/f4goh/status/1127602784210079746
Tests by Fred Moses W8FSM:

Tests by Shawn Garringer
DB0DMO by Frank DD3JI
https://twitter.com/hashtag/db0dmo
DB0SOB by Fritz DJ2RF
https://db0sob.de/
https://www.qrz.com/lookup/DJ2RF
1- Pictures
f4hdk • 04/22/2019 at 06:19 • 0 comments

For later usage.

View all 6 project logs

Discussions

f1rzn wrote 04/05/2019 at 08:32

Ca fait des années que j'espère quelquechose dans ce style, qui nous redonne les mêmes possibilités que le packet radio mais en version moderne. Je me suis permis de partager sur le groupe AREDN (le successeur de BBHN) et sur 2 ou 3 autres pages. Ca me parait très complémentaire de l'AREDN. Franchement bravo et merci. J'espère qu'un jour on aura un satellite geostationnaire qui viendra compléter les possibilités terrestres que cela offre. Ca manque un réseau mondial de données radioamateur.

Are you sure? yes | no

f4hdk wrote 04/05/2019 at 12:27

Merci beaucoup pour ton retour. Préviens-moi si tu veux tester cette solution. Tu as mon e-mail si besoin : f4hdk[at]free[dot]fr

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[deleted]

[this comment has been deleted]

f4hdk wrote 04/04/2019 at 17:17

Merci!

Are you sure? yes | no

bferrell wrote 04/03/2019 at 19:58

In regards the 433Mhz ISM module, Adafruit has one for just a bit under $10 US

Are you sure? yes | no

DL4APT wrote 04/03/2019 at 12:06

if i find the time i will look into modifying the design to use this much cheaper Ethernet module (same chipset but less then 4€ compared to the 20€) https://de.aliexpress.com/item/Free-Shipping-Q00216-1-Piece-USR-ES1-W5500-Chip-New-SPI-to-LAN-Ethernet-Converter-TCP/32435030006.html

Are you sure? yes | no

Jackson wrote 04/03/2019 at 03:56

The DMR radio amplifier is available here: https://www.radioddity.com/collections/mobile-radio-amplifier/products/vgc-vr-p25ud

Up to 40W output, really powerful

Are you sure? yes | no

Richard Green wrote 04/02/2019 at 21:45

I'd like to experiment with this in the USA. I can't seem to find a source for several of the critical parts. Farnell has a subsidiary nearby, called Newark Element14, and all the small parts are available there. The PCB I can get manufactured locally. But two of the modules seem to be unavailable. The itead LM2596 voltage regulator module is listed as 'Retired' on their website, and I have not found any source for the RF4463 F30 module at all. aliexpress carries a 'demo board' carrier for it and similar, but not the modules themselves.

If I can find sources for the parts, I'd consider doing a mass order, and making up kits to sell at the big Hamvention next month.

I do have one concern about the protocol itself. For the most part, NPR concerns itself only with the Physical and link layers, but why does it also act as a DHCP server? Why not keep it pure and leave that to the IPv4 router? And allow other protocols (ICMP, IPv6) as well?

Are you sure? yes | no

f4hdk wrote 04/03/2019 at 03:23

LM2596 module is available here (and many other places) : https://www.banggood.com/10Pcs-LM2596-DC-DC-Adjustable-Step-Down-Power-Supply-Module-p-963307.html?rmmds=buy&cur_warehouse=USA

RF4463F30 : https://www.tindie.com/products/NiceRF/rf4463f30-1w-wireless-transceiver-module/

or https://www.nicerf.com/product_179_237.html

About your last question: a NPR client acts as a DHCP server, because inside a NPR network, IP are assigned dynamically among clients, and the protocol do not carry Ethernet overhead but diretcly carry IP packets (therefore DHCP is not relevant in the radio part). I plan to allow "static IP" assignment for clients, but I don't know when I will be able to program it., and/or if the small microconrtoller will have enough ressources.

Are you sure? yes | no

Richard Green wrote 04/03/2019 at 13:25

OK, I'm beginning to get it. I ran into this once before with an external Wifi-Ethernet bridge called a 'game adapter' which did not carry ethernet MAC of the client across the Wifi link, but chose proxy ARP with its own MAC instead. Therefore, DHCP server on router would only hand out a single IP lease. Not suitable for multiple client machines at remote end.

Better to carry full ethernet header within NPR. More overhead, but more universal application.

Are you sure? yes | no

f4hdk wrote 04/03/2019 at 16:16

@Richard Green With NPR, can of course put several IP machines (PCs) behind one single client modem. Just set 'client_req_size' to more than one. Take a look at "advanced user guide", especially 'annex 5' and 'chapter 6.2'.

Are you sure? yes | no

Richard Green wrote 04/03/2019 at 16:29

Yes, I saw that. I still see that as a workaround, a hack, rather than a simple, standards-compliant solution. It would be far better, more adaptable, more universal, if NPR functioned as a fully transparent network bridge in the ISO sense.

Are you sure? yes | no

RipperFox wrote 04/08/2019 at 02:14

About the microcontroller: Ever thought about using an ESP32? I think they are cheaper and even faster + come with WiFi, wired ethernet can be added with a 1€ board (see e.g. https://sautter.com/blog/ethernet-on-esp32-using-lan8720/)
Thanks for your project!

Are you sure? yes | no

DL4APT wrote 04/03/2019 at 10:40

Nice RF has an aliexpress store: https://de.aliexpress.com/store/1087605 and they also have the RF4463F30 on sale (a lot of them just don't use a space in the name an the search will find a lot or go on the nicerf store to the menue point silconlabs)

Are you sure? yes | no

Daniel Roseman wrote 04/01/2019 at 01:11

Question for you. Does this protocol pause to identify itself? If so, how? What happens if I don't 'set' the callsign in the firmware? I read all of the docs, and I can't find where it identifies itself to the world at large.

Are you sure? yes | no

f4hdk wrote 04/01/2019 at 04:37

Sorry, I'm not sure that I understand the question "Does this protocol pause to identify itself?" English is not my native language.

You can find some answers in the "protocol specification", paragraph 6.3.

Are you sure? yes | no

Daniel Roseman wrote 04/01/2019 at 20:59

Under American law, Amateur radio stations have to pause and identify themselves at least every ten minutes.

47 CFR § 97.119 - Station identification.

https://www.law.cornell.edu/cfr/text/47/97.119

Are you sure? yes | no

f4hdk wrote 04/01/2019 at 21:04

OK Daniel. The NPR modems transmit their callsign (plus the callsign of the peer modem) every 2 seconds. The callsign can contain up to 13 characters.

Do you think that it's enough reguargind the US law that you mention?

Are you sure? yes | no

robert.ehresman wrote 04/01/2019 at 21:47

I do not believe the Who message as described in 6.3 would be compliant station identification in the US. Station identification requires inclusion of the Call Sign. While quite useful, the Who message information would also not be legally necessary here.

Sorry I was typing this while you answered Daniel. 13 characters would be sufficient.

But it sounds like the specification needs an edit.

Are you sure? yes | no

f4hdk wrote 04/02/2019 at 03:19

@robert.ehresman I do not understand your point. Why do you think that the WHO feature of my "New Packet Radio" is not compliant? It already includes the callsign. Refer to §6.2 of the spec also.

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Michael wrote 06/16/2023 at 23:44

FCC Part 97.119 requires that a station ID itself every ten minutes by CW, Phone, RTTY, or Image. Does the NPR modem do that?

Are you sure? yes | no

fabian wrote 03/31/2019 at 18:19

please add linux. And mobile power 24h/365 day

Are you sure? yes | no

f4hdk wrote 03/31/2019 at 18:46

The modem is OS independant. It connects to a host (PC) via Ethernet. Therefore, it is already compatible with Linux.

Have you read all the documentation?

About "mobile power 24h/365d", I have not understood what you expect. Please clarify that.

Are you sure? yes | no

fabian wrote 04/01/2019 at 11:06

comaptible != linux inside and power offgrid

Are you sure? yes | no

Ken N8KH wrote 03/27/2019 at 02:47

I have not yet received an answer to my question: are kits available. Are the motherboard (and daughterboards) available for purchase? How much??

Are you sure? yes | no

f4hdk wrote 03/27/2019 at 04:23

Hello Ken. I'm only a hobbyist, I have other things to do in my life, that's why I don't reply rapidly. Please be patient.

About kits, I don't know if I will be able to ship outside Western-Europe. If someone in the US can organize that for US people, it would be great.

The price for one modem kit is about 80€ here, plus shipping.

Please send me an e-mail to f4hdk[at]free[dot]fr and I will keep you informed. But once again, you will have to be patient, it will take weeks, months to organize that.

Are you sure? yes | no

Ken N8KH wrote 03/28/2019 at 02:24

I'm very interested in this project, and also helping you to write software and/or develop hardware. I've been interested in high-speed data radio for about 2 decades or more.

I've also looked into the Silicon Labs chip-sets in the past, and found them very interesting. I'm glad to see that you've taken my ideas with Silicon Labs chips farther than I ever did.

Are you sure? yes | no

k0elr1 wrote 03/28/2019 at 00:03

I wouldn't get too excited about this. By my reading of the US rules (specifically, parts 97.305(c) and 97.307(6), data transmissions are limited to 56 kilobaud and 100 kHz bandwidth in the 70 cm band. I could be wrong, but I'd check before I ordered anything.

Are you sure? yes | no

Ken N8KH wrote 03/28/2019 at 02:21

> data transmissions are limited to 56 kilobaud

> and 100 kHz bandwidth in the 70 cm band

You are correct.

But it is a stupid rule. It should be rescinded.

And I understand that it is fairly easy to get an experimental license to operate in (or out of) the amateur bands. So it could be used under an experimental license.

Are you sure? yes | no

robert.ehresman wrote 04/01/2019 at 21:02

Gentlemen, I direct you here for the 2005 ARRL legal brief position on broadband data transmissions in 70cm as they interpret CFR 47 Part 97.3 FCC regulations.

http://www.ntms.org/802.11/ARRL%20Board%20of%20Directors%202005.doc

Read it yourself, of course, but the summary conclusion by the League legal team is that if a data transmission method MAY be used to carry encoded video combined with other information (whether the video is actually present or not) the FCC would therefore classify the emission as Amateur Television, and the allowable transmission bandwidth can be at least 9 MHz on amateur allocations above 420 MHz. I am aware there are some groups and individuals in the US that have been operating HSMM or Broadband Hamnet style 802.11 based mesh radios in the 70cm band (radios by Xagyl or Doodle Labs) for years. This has probably never been tested in court or as far as I know any sort of enforcement action mind you, but that is why we have the League and why they established such a position at the beginnings of HSMM. Regionally there may be a conflict with common practice such as properly coordinated ATV repeater coverage. I believe effective video teleconferencing has been accomplished at rates well below 500 kbps for decades.

Are you sure? yes | no

cottsak wrote 03/26/2019 at 06:10

What's the point-to-point tested range and some throughput data for said test? Also do you have images of the antennas?

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f4hdk wrote 03/27/2019 at 05:45

We have not tested maximum distance for point to point links. But you can achieve big distances with high gain Yagi antennas at both sides of the link.

Are you sure? yes | no

Ken N8KH wrote 03/28/2019 at 02:22

My napkin calculations about a decade ago resulted in about a 25 mile range for two stations with 200 kHz bandwidth, 20 W each, and a vertical omni-directional antenna with about 6 dB of gain, and some moderate feedline loss.

Are you sure? yes | no

f4hdk wrote 03/28/2019 at 13:04

@Ken N8KH about your distance calculation...

Warning, omnidirectional antennas are hard to use at such high Symbol Rates (up to 500kS/s), due to "multipath" issues. You should prefer directional (Yagi) antennas, at least on one side of the link (client side). I will probably add explaination about that inside the documentation.

If you want to discuss more about that, do not hesitate to switch to the "public chat room" of my project.

Are you sure? yes | no

Ken N8KH wrote 03/26/2019 at 03:35

Are kits available for the modem?

Are you sure? yes | no

shawn wrote 03/25/2019 at 16:38

I see you mention a kit in your presentation. Count me in if you are trying to gauge overall interest.

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[deleted]

[this comment has been deleted]

f4hdk wrote 03/24/2019 at 09:22

Hello, you can refer to the table on page 18 of the "introduction document": RF bandwidth is 750kHz for 500kbps of net-effective datarate, over a 1Mbps channel. It is similar to DATV SR-500kS/s. Like for DATV, we use directional antennas.

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Erik Finskas wrote 11/13/2019 at 10:40

Are the RF bandwidths similar on GMSK than with GFSK? The documents refer to GFSK but I understood the v2 protocol uses GMSK

Erik OH2LAK

Are you sure? yes | no

NPR New Packet Radio

Description

Details

Documentation

PCB Design (Gerbers, BOM, etc...)

Modem Firmware : binaries and sources