dPMR Interoperability - Why Do We Need IOP Testing?

dPMR is designed to be a multi-vendor system in which many manufacturers develop and market different equipment to suit varying customer requirements but with all of them based on a single set of standards that allow customers to have a choice of vendors, equipment and features. In this way, any number of manufacturers' radios should be capable of working with each other on any other system approved to the same level. For instance, there may be a requirement in a single system for both standard hand-held radios to work alongside intrinsically safe or waterproofed models.

It could be difficult to find a single manufacturer to satisfy all these requirements but easier to find different manufacturers which can supply one or other of them. In the dPMR world, there are a number of international standards with which radio manufacturers must comply in order to be called “dPMR”.. These are published by ETSI and are developed and maintained by the TGDMR group, to which many dPMR Association members contribute on a regular basis. So for the protocol levels we need to look at:

TS 102 490 for unlicensed dPMR 446 equipment

TS 102 658 for licensed dPMR equipment

These in turn call up EN 301 166 to define the minimum requirements to satisfy the EU commission for operation under the R&TTE directive (other regulatory bodies may have different requirements) and TS 102 587 for basic inter-operability testing.

However, there are a number of areas that are not covered by the ETSI documents, either because they are not required in order to satisfy the regulatory bodies or have been left specifically for the manufacturers to implement as they see fit to suit their particular markets and/or customer requirements. As a result, there are a number of design decisions that manufacturers need to make during the development of their equipment which could mean that their equipment may not work completely with other manufacturers’ equipment. The dPMR Association therefore defines a number of parameters in addition to those in the standards that, when coupled with practical testing of the devices involved, means that the specified operations have been rigorously tested and compatibility between any devices bearing the same level of “dPMR” logo can be guaranteed.

What is IOP testing?

The dPMR Association publishes a test procedure for each class of dPMR equipment:

dPMR 446 ISF and CSF modes TS 102 490 license–free equipment

dPMR Mode 1 TS 102 658 peer-to-peer mode

dPMR Mode 2 TS 102 658 repeater mode

dPMR Mode 3 TS 102 658 trunked mode

The association also publishes additional tests for areas not covered by the existing standards that would affect interoperability, which principally cover RF and modulation aspects. These are required as EN 301 166 is a very generic standard and does not cover some of the specific aspects that are required for dPMR operation.

The IOP test checks the operation of a particular manufacturer’s device against existing devices that are known to work. Not all features in the standard have to be implemented but if are, they must be done in the specified manner. Each manufacturer must declare which features are supported (as shown in TS 102 578-1 – PICS for TS 102 490 operation, or TS 102 726-1 for TS 102 658 operation) and which IOP test profile the equipment is intended to support. In this way a user can be assured that a particular feature in any radio displaying the dPMR logo will work with any other as they will have been tested against the IOP schedule by the dPMR Association.

IOP testing takes place at places and times decided by the dPMR Association and its members and brings together a number of manufacturers which then test their equipment against each other by placing calls of various types (individual, group, short data, status etc. according to the appropriate performance profile) under the watchful gaze of the Chairman of the dPMR Association Technical Working Group, who is there to ensure that the tests are carried out properly. All over-air transactions are logged and may be re-called to help analyse problems or demonstrate compliance and ensure repeatability.

The first IOP testing was performed at CML, Maldon, UK in April 2011 between Icom equipment and the CML ATB010/DE6181/PE0002 test/evaluation cards.

The second IOP test session was performed at Sicomm, Wuxi, China in October 2012 and covered a number of Mode 2 portables as well as repeaters and mobiles in both VHF and UHF bands.

Before granting an IoP certificate, each member shall supply or declare the following for each equipment submitted:

• Compliance with EN 301 166
• A completed PICS document (TS 102 578-1 or 102 726-1)
• Test Profiles applicable
• Completed IoP test report (including additional RF testing)
• IoP test log file(s)

Once the TWG Chairman is happy that the testing has been successfully completed, a certificate to that effect will be issued and the equipment added to the approved list maintained by the dPMR Association. Certificates and the use of the dPMR logo are reserved solely for members of the dPMR Association. Non-members will be supplied with a Test Report.

IOP Test Process

Testing Costs

IoP testing is a collaborative process and so each member of the dPMR Association submitting equipment for testing is expected to cover their own costs. Non-members will be charged 600euros per submission. In addition, the host may require a small fee to cover any costs of equipment or premises hire etc, which will be agreed prior to the start of the test session.

Applying for IOP testing

Manufacturers wishing to apply for IoP testing should first contact the dPMR Association secretary or TWG Chairman who will then co-ordinate with other members to establish a suitable time and place. IOP testing is open to both members and non-members of the dPMR Association. However certificates can only be issued to member and non-members will receive a Test Report.

Documents relating to IOP testing

Please contact the secretary if you wish to receive any of the documents relating to interoperability testing: Email: secretary@dpmrassociation.org


What is IOP testing?


dPMR™ Product Class Interoperability Classification Guide

To assist users in the selection of appropriate dPMR products and solutions for specific applications, the dPMR Association have introduced Product Classes to distinguish between the compatibility and capabilities of different dPMR compliant equipment. This interoperability classification is principally required for TS 102 490 compliant equipment (e.g. for dPMR446), where different compliant Vocoders are permitted but will not inter-work with each other.

For TS 102 658 equipment operating in FDMA protocol with a channel spacing of 6.25 kHz, the dPMR Association have standardised the AMBE+2 Vocoder, so users can be sure that any unit which has passed inter-operability (IOP) tests and been granted an IOP certificate and the right to display the dPMR logo, will be interoperable with other equipment of the same Class.

In the cases of Class A (AMBE +2 Vocoder) and Class R (RAWCWI Vocoder), equipment of the same Class will offer full interoperability irrespective of manufacturer, while combining the use of equipment from different classes could result in limited functions being available.

Class M equipment employ a manufacturer specific Vocoder and therefore Class M marking of a product serves as a warning to users that it may not work with any other class and, in addition, may not work with Class M equipment from another manufacturer. Product classification marking of TS102 490 unlicensed dPMR 446 compliant equipment:



 Vocoder Type



 RALCWI™ Vocoder

Full interoperability with other Class R equipment.
Limited interoperability with other dPMR Classes.


 AMBE+2™ Vocoder

Full interoperability with other Class A equipment.
Limited interoperability with other dPMR Classes.


 Manufacturer Specific Vocoder

May not work with other Class M equipment.
May not work with other dPMR Classes.

Product Marking