Herald App (Herald Protocol) Results 2021-01-31


A formal test on 4 phones (2 iOS, 2 Android) carried out on 31 Jan 2021 by Adam Fowler of the Herald Protocol development team as a pre-release test for Herald v1.2.0-beta3. These are the same 4 phones used for all Herald minor version and beta version performance regression tests.

Herald v1.2.0-beta3 introduces cross-protocol interoperability, enabling capture of payload data and RSSI measurements for the Herald protocol, and other connection and advert based protocols, such as OpenTrace, at the same time. Changes were also introduced to reduce memory and computation overheads, and improve consistency in event callbacks across Android and iOS.

Continuity has remained at > 99.9% between the 4 phones in the test during a full 13.5 hour period. Mean time between RSSI readings is 1.93s. Battery usage was reduced to 1.2%, 1.6%, and 1.6% per hour for the Samsung A10, A20, and iPhone 6+, down from 1.9%, 2.2%, and 2.5% in previous test (see 2020-12-08). The iPhone 6S battery is faulty, thus excluded from battery usage analysis (see 2020-12-08 for details).

The test was deliberately ran on known problem phones. A Samsung A10 on Android 29, Samsung A20 on Android 28, iPhone 6+ on iOS 12.4.5, and iPhone 6S on iOS 12.1.4. The Samsung A10 and A20 both rotate their BLE MAC address every few seconds, and the iPhones 6+ and 6S are test devices with worn batteries that have been in use since 2014 and 2015. The raw log data is available here for analysis and inspection.

Completeness has not been recalculated, but is likely to be higher. We have used the current known value for this until a full 10 device test can be ran.


Measure Result Notes
Overall Efficacy 41.29% Effective
(UK MAX 46.57%)
Probability of detection 94.19% Formal RISK detection
Phone Detection 100% Includes iOS in the background
Continuity 99.95% Full continuity
Completeness RT1 98.36%
Completeness RT2 TBD Not yet calculated from data
Completeness CE 95.95%
Accuracy 95.95% RSSI accuracy
Longevity 99.86% 13.5 hour test
Mean time
between readings
Country UK
Have BLE Phones 72.53% OFCOM reports
Hardware Support 98.19% BBC data
Software/OS Support 98.00% BBC data
Overall Pspec 69.79%
Pspec squared 48.71%

Phones tested

PhoneId Phone Make and Model OS and version Known issues
1 Samsung A10 (SM-A105FN) Android 28 A10s knowingly rotate their BLE MAC address with every request. Herald uses an ephemeral ID that rotates every 15 minutes as a performance improvement.
2 Samsung A20 (SM-A202F) Android 29 Same issue as A10, above.
3 iPhone 6S iOS 12.1.4 Phone name is Denmark. Battery is faulty and near end-of-life as it loses charge in steps.
4 iPhone 6+ iOS 12.4.5 Phone name is Netherlands.

Fair Efficacy Stats Summary

Phones Max Pairs Pairs Detected Detection Percent Max 30 second windows 30 second windows achieved Missed windows percentage Longevity change over 13.5 hours
4 12 12 100% 20040 20029 0.0549% 0.139%

Phone detection and distance estimation reports

The below 4 charts show discoveries, ID (data payload) reads, and RSSI (distance estimation) readings as individual dots.

A10 results A20 results iPhone 6S results iPhone 6+ results

The below charts show RSSI variation over time. In a formal 12 hour test these will mostly be static.

A10 RSSI A20 RSSI iPhone 6S RSSI iPhone 6+ RSSI

Battery usage

The below table and chart shows battery charge remaining over time. Note the iPhone 6S has a faulty near end-of-life battery that loses charge in steps (see 2020-12-08 results).

  Samsung A10
Samsung A20
iPhone 6S
Start time 2021-01-31 19:26:40 2021-01-31 19:27:36 2021-01-31 19:28:13 2021-01-31 19:28:14
End time 2021-02-01 08:52:24 2021-02-01 08:53:20 2021-02-01 08:55:34 2021-02-01 08:55:43
Start battery 100% 100% 100% 100%
End battery 84% 78% 66% 78%
Elapsed 13h 25m 44s 13h 25m 44s 13h 27m 21s 13h 27m 29s
Usage per hour 1.19146% 1.63826% 2.52679% 1.63471%
Notes N/A N/A End of live Battery N/A

Battery Level

Getting Started

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