Pocket DAB Radio Sensitivity
This article was originally published in July 2016. Since then, the author has retested the radios alongside three other new radios under a more accurate testing regime. The original article has been archived here and here.
TL;DR: The Pure Move R3 won by a margin in numbers terms. However for those in marginal or weak signal areas, the Pure Move 2500/20 will perform better. The VQ Blighty, Roberts Sports DAB 2/6, Majority Petersfield (Romsey and Parkside) and Signstek HRD-101 follow respectively.
Despite being one of the most important aspects of a pocket digital radio, little information is available for the consumer regarding the sensitivity of the tuners and stability of the software to decode DAB(+) signals and receive FM transmissions.
Failure to get this basic, fundamental aspect right can result in unhappy consumers, reduced confidence in the medium and nervousness in the future to invest in similar technology.
This is more of an issue for mutliplexes where either financial or regulatory constraints limit expansion and strengthening of transmissions. Such as Sound Digital’s national rollout being limited to around 75% of the population or minimuxes across the UK where Ofcom has limited transmission power to 200W (previously 100W).
At the time of writing, information on pocket DAB radio sensitivity is restricted to a number of places:
- An Ofcom report into DAB radio sensitivity. The document mentions two personal radios but doesn’t identify them;
- Magazine reviews if the radio you are interested in has been reviewed — even then, information is subjective and could be down to the reviewers choice of station and multiplex it broadcasts on! Which leads to;
- Which? magazine, who conduct tests on radios but places their reviews behind a paywall, or;
- Personal reviews on shopping websites. The same downsides can be found there as with magazine reviews.
The author has decided, at his own expense, to test out the sensitivity of several well known and popular pocket DAB radio sets as well as their ability to hold onto a signal for extended periods of time. In the hope that he can provide an objective, fair and helpful guide to consumers and help invigorate the radio manufacturing industry to excel in this area.
There are numerous factors which can can affect the reception of signals and the stability of decoding a signal on a pocket DAB set:
- Signal strength. Consumers are advised to do a check using their house number and postcode to predict the stations they’ll receive and how strong the signal is;
- Tuner sensitivity. How sensitive is the tuner in finding multiplexes when scanning and maintaining a signal;
- Firmware stability. It was noted in the mobile testing that some sets were better at dealing with error correction and signal stability than others;
- Headphone lead. Pocket DAB radios use the headphone lead as the antenna. Some radios also include a mini telescopic aerial. In the tests below, the same headphone lead was used for all the tests conducted and any telescopic aerial was contracted. Some of the radios tested do include their own headphones that the manufacturers recommend you use.
There were two main tests to establish a general idea of how sensitive the digital radios were. A mobile test which determined how stable the signal was when used in a pocket on the move and a stationary test where the radios ability to pick up signals from DAB multiplexes were tested.
The radios tested are as follows:
The radios tested range from around £20 (Signstek HRD-101) up to just over £200 (LG Stylus 2) but all can be found at varying prices and condition via online and high store retailers. All the radios tested have a rechargeable battery (all except the Oxx, Roberts and Yaakin radios use the Micro USB standard connector, though the latest iteration of the Roberts Sports DAB line replaces the DC jack input for a micro USB input), support for DAB+ and the full Band III frequencies 5A-13F (the Pure Move 2500/20 also supports DMB-R and L-Band).
At the time of writing, the Majority Petersfield Go is the best selling pocket DAB radio (and third best selling overall DAB radio) sold on Amazon UK.
Only four of the radios in the test have the voluntary Digital Radio Tick mark on the packaging, designed to be awarded to radios which meet minimum standards set by the Department of Culture, Media and Sport in the UK and granted by Digital Radio UK — the Azatom, Pure Move R3, Pure Move T4 and the Sony. The Pure Move 2500/20 is also certified on the Digital Radio website.
The LG Stylus 2 has two apps which can be used to listen to DAB+ Radio, LG’s own DAB+ app which has basic functionality for listening to the radio whilst the Radioplayer app, downloadable from the Google Play Store, can use both DAB+ and Internet Radio and switch between the two in real time. This can cause a peculiar issue where DAB+ is broadcast live whilst Internet Radio by design is buffered by up to a minute, switching from one or the other creates a significant jump or repeat of the service being listened to. For these tests, the author has used LG’s DAB+ app.
Initially the author used a 1.5m headphone wire attached to Intempo headphones. These headphones are no longer made and in recent tests, an analogue substitute which give the same signal strength results have been used. As mentioned, all telescopic aerials were contracted.
At the time of writing, the area the author lives in receives the following multiplexes:
Sadly, no minimuxes are broadcast in this area to test the experience of low powered transmissions with a pocket DAB radio.
These are not full-on scientific tests done in labs with sound proofing, micro multiplexes and laboratories. That is beyond the capability financially of the author! These are basic functionality tests to gather a general idea of the tuner sensitivity and stability of signals in real world scenarios where people would use a pocket DAB radio — in a pocket on the move or in a building for personal listening.
Two tests were performed to determine the sensitivity and stability of the pocket DAB radios using different signal strengths and surroundings.
The first test took place in a suburb in the authors home town. The route selected includes a open grass area, alleyways, paved residential areas and typical suburban roads — the things you would expect in a normal suburb. The radios were tuned to Jazz FM Stereo on the Sound Digital multiplex, broadcasting in DAB+, using equal error protection level 3A (the standard for UK digital radio) and Reed-Solomon error protection.
For both the suburban and urban tests, a stable signal was determined if a error free listening was attainable within a time frame of 0.75 seconds (the time it takes to make a pace at casual walking distance). For the suburban test, the radio was placed in a coat pocket with the headphone socket aimed downward to ensure taller DAB radios were not given a height advantage that would skew the results. The headphone lead was allowed to string across and freely to ensure maximum signal reception. The results were as follows:
The Roberts won this test by a hairs length, with the two Pure radios virtually tying in second and third respectively. The Majority Petersfield and Oxx were close behind. The Kitsound, Yaakin, LG Stylus 2 and Lava performed incredibly poorly under medium signal conditions. The Reka managed to not pick up any signal at all.
A second test was performed in an urban setting, using a route that took in normal road arteries, open squares, closed alleyways and streets with clustered and large buildings. A typical urban setting. This time, all the radios were tuned to LBC on the Digital One multiplex which uses unequal error protection level 3 on a strong multiplex which is slightly weaker than the Sheffield multiplex but stronger than the BBC National DAB multiplex. A good all rounder. The test results were as follows:
The Pure Move R3 won this test with the VQ in second putting the Pure Move 2500 into third by a mere 0.01%. The Roberts which won the suburban test had a few more dropouts than VQ or Pure. Most radios coped well under a strong signal in an urban area, including the LG Stylus 2, Logik and Yaakin which did incredibly poorly in the medium signal suburban tests although the Reka continued to perform poorly compared to other radios.
The author conducted a number of tests with solely the headphone wire for an antenna, headphones to listen to the audio for any dropouts and a full autoscan was performed to determine the number of services each radio could receive. The tests were done in both an indoor urban setting in the middle of the authors home town and an indoor suburban setting at the edge of the authors home town. The results were as follows:
SA = Service area multiplexes (11A, 11C, 11D and 12B); OA = Out-of-area multiplexes; T = Total
The Pure Move 2500/20 and R3 radios win across the board when it comes to finding stations and maintaining a stable signal without unrecoverable signal errors causing dropouts. The Majority Petersfield, Signstek and VQ performed well respectively.
The Pure Move R3 which did well in the urban stationary test, did not do so well with weaker signals from several multiplexes on the suburban one. From experience of using the radio, the autotuning and initial finding of stations is slightly weaker than the 2500/20 but slightly outperforms the 2500/20 when tuned. As the radio lacks a manual tuning function, its unlikely to be of an issue to most people.
The Oxx has a quirk where it can end up picking up less stations in a scan than its nearest competitors. Worth noting the hybrid pocket and portable DAB radios did less well, particularly the Sony XDR-P1DBP. It is worth noting that if telescopic aerials were allowed in this test, the Sony would have done better and pick up as much as the Roberts did with only the headphone lead as an antenna. However, such an arrangement in a public setting may not be practical or desirable.
One thing to note with the manual tuning setting (not tested in this test) on the Azatom is that there is a bug on weak-medium signals. The radio will tune to the multiplex for a brief moment before showing no signal. Sadly, as the firmware is locked and cannot be upgraded, this bug can only be fixed with a newer revision release. Also, the Lava will become unresponsive for several seconds after tuning or in weak signal conditions. Again, this radio cannot be upgraded either and can only be fixed with a newer revision release.
Follow-up Weak Signal Test
Noticing the gap between the Move R3 and Move 2500/20 with a strong signal and the Move 2500/20 edging the Move R3 by a small amount — virtually tying for the runner-up spot—as well as the 2500/20 doing better tuning in to weaker multiplexes in the suburban testing, the author did a follow up test using the same route as the suburban mobile test. This time the Move 2520, Move R3 and Roberts Sports DAB 2 radio (which won the suburban mobile test) were tuned to Chill on the Nottinghamshire multiplex which uses protection level 3 and with a sensitive portable radio, can be picked up with very careful position or (preferably) with an external dipole, log periodic or yagi antenna connected to a DAB tuner.
The results were as follows:
Interestingly, the winner of the suburban test with a medium strength signal has a far better time maintaining such a signal but when the signal is weak or marginal, the radio suffers from far more drop-outs than the Move radios. Also of note, as per the suburban result, the Move 2500/20 has a better threshold for maintaining a signal than the Move R3.
While the vast majority of people will not accept dropouts for radio reception, if you are in an medium to weak signal area for a multiplex, the Move 2500/20 will less likely suffer the odd dropout and maintain a weak signal than the Move R3, the Roberts and all the other radios covered in this article.
The same can be said regarding autotuning. The Move R3 has a higher threshold for when it accepts a multiplex and in turn, display stations on that multiplex in the station list. The vast majority of people will likely not be concerned about this but if you are more interested in a Move radio that can tune to weak multiplexes (ie. for DXing), the Move 2500/20 is the more sensitive radio in this regard.
Something noted as is the case with new Verona 2 chipset radios I have used is that the signal meter fluctuates more widely compared to previous chipsets, including the Chorus 3 chipset used in the Move 2520. This might explain the odd additional dropout, on the Move R3 even if that radio is more sensitive than the Move 2500/20 range overall. This may account for the poorer performance with weak signals, lower amount of multiplexes detected in autotuning and the odd dropout in the medium signal test compared to the Move 2500/20. And it will also explain why in a crowded urban area on a medium strength multiplex sans interference, the Move R3 will pick up more signal than the Move 2500/20. I also noted that the Reka which uses a Frontier Silicon Siena module (and same fonts and screen layout as the Move R3 if not its performance) performs better stationary than mobile. I’m not sure if this could be resolved with a firmware update (or if it would be resolved, the less sensitive autotuning could be a way to prevent weak signals being detected and disappoint users thinking they have more stations than they can get a stable signal for).
Tests were also made to determine how quickly the radios could maintain a signal to quickly decode an audio stream or in the event of losing signal lock, how long the radios take to start decoding the audio stream.
The Goodmans and Oxx radios are able to maintain a signal lock indefinitely (ie. they do not attempt to retune as all the other radios do) until you change station but still takes a little time to recover (see below) when it regains a useful signal. The Roberts will not attempt to retune for around 20 seconds. Most radios wait about five seconds to quickly recover before retuning.
The Yaakin was the quickest to recover a signal and resume playing audio followed by the Majority Petersfield Go, Kitsound, Logik and LG. However, the majority of these radios were not the best performing in the suburban and urban mobile tests. All the radios recovered within 2.5 seconds of losing signal lock except for the Pure Move R3 which has a feature that it will quieten the sound when retuning. Worth noting that this quietening of the sound only happens if you lose signal lock.
A word about antenna performance
The other critical component of a digital radio set-up is the antenna. Whilst a few of the radios on test have a miniature telescopic antenna, this shouldn’t be extended whilst being used in a pocket (unless you’d like it to break instantly). All the radios on test use the headphone lead to pick up radio signals. The majority of radios on test supply their own in-ear headphones with cable lengths between 1m and 1.2m. A few do not to keep costs down, namely the Azatom and Goodmans whilst the Sony is designed as a portable radio first with pocket radio capability included so also does not contain headphones.
From use of various headphones, I have found the sweet spot for cable length when used out and about is 1.5m. The 1.2m cables provided with the Pure and Oxx work just as well but did introduce the odd dropout which didn’t occur with headphones using a 1.5m lead. The shorter 1m cables were slightly worse in reception quality. The optimum length for an antenna wishing to receive DAB(+) in the UK at half a wavelength is between 77.3cm (block 7D) and 65.5cm (block 12D) — which a 1.5m cable can roughly reach untangled if the radio is placed within a coat or trouser pocket with the rest of the cable looping back up into the pocket where the radio is contained.
The price of the headphones did not matter in terms of reception — a £6.99 pair of Intempo headphones from B&M Bargains (no longer sold) kept up or even surpassed slightly the reception of DAB signals from a £250 pair of Sennheiser headphones used in the original tests — both use a 1.5m cable. There is virtually no difference in reception whether the headphones split the cable in two to each speaker or whether the wire went to one speaker then over the headphone band to the other or in terms of the thickness of the plastic protecting the cable. Obviously, cables work better as an antenna when untangled.
Whilst the sound and build quality of the Intempo headphones will be trampled upon by the Sennheiser ones, for low bitrate DAB listening, sound quality is not a primary focus of concern as opposed to radio reception.
In terms of which pocket to place the radio, that will be down to personal preference and which direction the signals are coming from for best reception — something only the user can experiment and decide upon. The other issue with picking up reception using a headphone lead is you — but there isn’t much you can do about that — the main factor for signal strength as demonstrated in the aforementioned ERA Technology study for Ofcom is the position of the headphone cable.
Where problems did occur were with headphones using 3m cables, notably the cheapest Sennheiser on-ear headphones. Even when tidying up the cable so as to make it a shorter length for convenience, losses were apparent and the signal strength was degraded considerably to the point of consistent dropouts which would not occur with 1.2–1.5m headphones.
And for those who travel on public transport, for best signal reception, be as high up as possible (top deck of a bus is best), sit in a window seat or stand next to a window and have as much of the wire exposed to the window as possible in a vertical position to match the polarisation of the broadcasts. The metal framework of buses and trains causes signal loss as it works as a faraday cage. Also worth nothing that LED lights and signs used within buses and the electrical components of vehicles can create RF interference, so much so as to wipe out radio reception, particularly for DAB, up to several metres away, affecting people in cars, people walking along the pavement and in buildings close to the road.
The Pure Move R3 performed the best on average across the majority of the tests that were thrown at it. Subsequent testing has shown that whilst the Move R3 is marginally better, the Move 2500/20 performs better in marginal/weak signal areas and can pick up more during an autoscan than the Move R3. It is worth noting that the Majority Petersfield, Oxx, Roberts, Signstek and VQ would also perform well with a few dropouts even on medium strength signals if held in the hand or in a higher pocket with a slack headphone lead allowed to hang down for maximum reception.
But this leads to one question. At the time of writing, the Move R3 is expected to retail a penny shy of ninety pounds new whilst the Move 2520 is twenty pounds cheaper. Is the marginal increase in performance within strong signal areas worth the extra cost of upgrading? I suspect people will likely think not and the Move R3 will gain momentum once the price starts to fall and the 25xx range is discontinued.
- For medium to strong signal areas — Pure Move R3: Won the mobile urban test and the urban stationary test. Performs better in strong signal areas compared to its predecessor…
- For weak signal areas — Pure Move 2500/20: Very close in performance to its younger brother in strong signal areas, performs better than its replacement in weaker signal areas and won the suburban stationary test. Also has the advantage of being cheaper.
- VQ Blighty: Did very well on the urban test and suburban test and performed good on the signal lock test. A good radio for use in DXing, managed to lock onto a distant weak signal in tests.
- Roberts Sports DAB 2/6: Won the suburban test, did well on the urban test and performed great for keeping signal lock. Also a good radio for use in DXing if used with its telescopic aerial, able to detect distant weaker signals.
- Majority Petersfield (Romsey and Parkside): Did well with slightly more dropouts in the suburban and urban tests. Did very well overall in the stationary tests. Also the second cheapest radio on test.
- Signstek HRD-101: Did well in the urban and suburban mobile and stationary tests, the cheapest pocket radio on test though build quality is an issue for people who have reviewed the radio on Amazon.
One noteworthy thing with the top performing radios is that they all use chipsets from Frontier Silicon. However, not all radios are created equally. The Pure Move R3 and Reka DB-355 use newer modules (the latter confirms itself to be using the Siena module) but the latter has significantly noticeable worse performance than the former and the former performs a little worse than its former version with an older module (Chorus 3). While the newer chipsets are a little more sensitive than the older ones and this showed when finding signals in the DX testing, it had more difficulty locking onto signals (as did the Move R3).
In practice, all but radios with the weakest tuners should easily maintain a strong signal without dropouts. For medium or “fair reception” signals, you’ll need a more sensitive radio to minimise disappointment. In terms of how well you will do with a pocket radio, from personal experience:
The usual caveat of “your mileage may vary” and I make no guarantees should apply here. Indoor and public transport reception, particularly in urban areas will be more troublesome than in suburb or rural areas and here, radio via Wi-Fi or mobile phone may be a better solution in some cases.
As the report I linked to earlier by ERA Technology commissioned for Ofcom correctly points out, telescopic aerials are a far better way of receiving DAB signals than a headphone wire. Where possible, I would advise you to use a radio with a telescopic aerial if you can, though on those pocket DAB radios with telescopic aerials, they can be very flimsy and easily bent or broken if handled incorrectly or have force put upon them. However, this is not practical in social settings or on the move.
One thing to note for those pocket DAB radios with exposed telescopic aerials. Do not touch them when handling them. If you do, the signal degrades significantly.
I hope my own investigation into this sector of the radio manufacturing industry will help consumers make an informed decision on their next pocket DAB purchase and spur the industry on to excel and improve the sensitivity and stability of radios for the benefit of everyone.
An addendum has been added in relation to DAB DXing and the manual tune options of the pocket DAB radios that support that option.
Update (03/03/2017): Added Logik LHDAB14 tuner sensitivity results and updated appearance of tables and results.
Update (30/09/2017): Added Kitsound PocketDAB and Yaakin WalkRadio K1.
Update (13/01/2018): Added Pure Move R3.
Update (16–20/01/2018): Additional testing and discussion between the Pure Move radios regarding weaker signals.
Update (03/03/2018): Added Majority Petersfield Go, Pure Move T4 and Signstek HRD-101.
Update (10/03/2018): Added Lava Kaliko
Update (15/04/2018): Added Reka DB-355