Short-range device
License-free low-power transmitters for short-range wireless communication.
A short-range device (SRD) is a type of radio transmitter used in telecommunications that is unlikely to cause harmful interference to other radio gear. These devices operate at low power—typically between 25 and 100 milliwatts of effective radiated power (ERP) or less, depending on the frequency band—which keeps their useful range to a few hundred meters. They do not require a license to operate.
Common short-range wireless technologies include Bluetooth, Wi-Fi, NearLink, near-field communication (NFC), LPWAN, ultra-wideband (UWB), and IEEE 802.15.4. These are implemented using RF CMOS integrated circuits. Roughly a billion short-range wireless chips ship each year, with Bluetooth making up over 55% of shipments and Wi-Fi around 35%.
Applications are wide-ranging and include power meters and other remote instruments, RFID tags, radio-controlled models, fire, security, and social alarms, vehicle radars, wireless microphones and earphones, traffic signs and signals (including control signals), remote garage door openers and car keys, barcode readers, and motion detectors.
In Europe, the European Commission, through CEPT and ETSI, mandates the allocation of several frequency bands for these devices, restricts their usage parameters, and provides guidelines to avoid interference.
According to ECC Recommendation 70-03, specific annexes define usage patterns, maximum emission power, and duty cycle requirements. For example, the 863 to 870 MHz band (SRD860) in Europe is license-free and can use FHSS, DSSS, or analog modulation, with a transmission duty cycle of 0.1%, 1%, or 10% depending on the sub-band, or Listen Before Talk (LBT) with Adaptive Frequency Agility (AFA). Although this band is classified as short-range, it is also used for LPWAN networks designed for long-range, low-bit-rate communication between connected objects.
In the 869.7–870.0 MHz sub-band, unrestricted voice communications are allowed with a channel spacing of 25 kHz or less and a maximum power output of 5 mW ERP. Handheld transceivers for the SRD860 band were briefly available in the mid-2000s but did not offer dual-band compatibility with PMR446 and LPD433 bands, and they have since been taken off the market.
As of January 2018, four RFID frequencies are also available for data networks, with a power up to 500 mW and a bandwidth of 200 kHz.
- Power limit
- 25–100 mW ERP or less
- Typical range
- a few hundred meters
- Annual shipments
- approximately billion units
- Bluetooth share
- over 55% of shipments
- Wi fi share
- around 35% of shipments
- European band
- 863–870 MHz (SRD860)
- Max power voice band
- 5 mW ERP
Lore & Background
Short-range devices are governed in Europe by ECC Recommendation 70-03, which defines several annexes encapsulating specific usage patterns, maximum emission power, and duty cycle requirements. The European Commission mandates through CEPT and ETSI the allocation of device bands, restricts parameters of use, and provides guidelines for avoiding radio interference. The 863–870 MHz band (SRD860) has been allocated for license-free operation using FHSS, DSSS, or analog modulation with transmission duty cycles of 0.1%, 1%, or 10% depending on the band, or Listen Before Talk (LBT) with Adaptive Frequency Agility (AFA). Unrestricted voice communications are allowed in the 869.7–870.0 MHz band with channel spacing of 25 kHz or less and maximum power output of 5 mW ERP. SRD860 handheld transceivers were briefly available in the mid 2000s but did not offer dual-band compatibility with PMR446 and LPD433 bands and have been put off-market. From January 2018, four RFID frequencies (865.7, 866.3, 866.9, and 867.5 MHz) are also available for data networks with power up to 500 mW and bandwidth of 200 kHz, subject to low duty cycle, LBT, and adaptive power control (APC).
Reader's Guide
Short-range devices are significant because they enable a vast ecosystem of license-free wireless applications, from power meters and remote instrumentation to RFID, radio-controlled models, security alarms, vehicle radars, wireless microphones, traffic signals, garage door openers, car keys, barcode readers, and motion detectors. Their low power and limited range reduce the risk of harmful interference, allowing widespread deployment without individual licensing. The SRD860 band, in particular, supports Low-Power Wide-Area Network (LPWAN) technologies designed for long-range communications at low bit rates among connected objects. The allocation of specific frequency bands and the imposition of duty cycle limits, LBT, and APC ensure coexistence among many users. The dominance of Bluetooth and Wi-Fi in annual chip shipments—over 55% and around 35% respectively—underscores the commercial importance of short-range wireless technologies, which are implemented as RF CMOS integrated circuits. The legacy of SRDs is their role in enabling ubiquitous, low-cost, and unlicensed wireless connectivity for consumer, industrial, and infrastructure applications.
Did You Know?
- Short-range devices are typically limited to 25–100 mW ERP or less.
- Bluetooth accounts for over 55% of annual short-range wireless chip shipments.
- The SRD860 band in Europe spans 863 to 870 MHz.
- From January 2018, four RFID frequencies in the SRD860 band are available for data networks with power up to 500 mW.
Frequently Asked Questions
What is a Short-range device (SRD)?
An SRD is a low-power radio transmitter built for short-distance wireless links that are unlikely to cause harmful interference to other radio equipment. It occupies the lowest tier of the radio-spectrum hierarchy in terms of both power and coverage.
What power limit applies to SRDs?
SRDs are capped at roughly 25 to 100 milliwatts of effective radiated power, with the exact ceiling depending on the frequency band in use. Keeping output this low is the core reason regulators allow them to coexist with licensed services.
How far can a Short-range device typically reach?
Because of their constrained transmit power, SRDs generally cover only a few hundred meters. That limited radius is a defining trait that sets them apart from medium- or long-range radio links.
Do I need a license to operate an SRD?
No—SRDs are license-free by design, which is why roughly a billion units ship every year without any individual regulatory paperwork. The low-power, low-interference profile is precisely what makes unlicensed operation acceptable to spectrum regulators.
Which technologies fall under the SRD category?
Common examples include Bluetooth (over 55 % of annual shipments), Wi-Fi (around 35 %), NFC, NearLink, ultra-wideband, and IEEE 802.15.4. In Europe, the 863–870 MHz band—often referred to as SRD860—is the dedicated allocation for these transmitters.
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