Chipset-based Radios

Self-Contained Chipset Radios

More recently, the Silicon Laboratories/Skyworks Solutions Si47xx and the NXP TEF6686/TEF6688 radio chipsets, have become very popular.  These radios use an ESP-32 microprocessor to control the display and user interface, and do not require an external computer for normal operation.  The Si47xx-based receivers can cover 0.1 to 30 MHz with both AM and SSB/CW modes, and the commercial FM bands.  The TEF chipsets provide similar frequency coverage, but only AM and FM demodulation, but no SSB/CW.   There are many variants of the Si4732-based ATS-25 the ATS mini,  the Si4734-based ATS-20 and  TEF6686 radios.  A few radios have both TEF668x and Si47xx chips.

Many of the small portable radios with video displays based on the Si47xx and TEF668x chipsets and ESP-32 microprocessors suffer from internally generated noise when they are used with directly attached whip and loop antennas.  The use of external antennas can reduce this noise.    In addition, the radios have limited dynamic range, which can lead to overload on strong signals.  The use of an external step-attenuator can alleviate this problem.   Most of these radios include rechargeable batteries that use USB chargers.

The user-interface of TEF668x-based radios often have tuning and buttons similar to conventional portable radios.  The Si47xx-based radios usually have a single knob combined with a pressure-switch that is used to switch between radio parameters and to adjust them.  Clunky and non-intuitive are the kinder descriptions of these user interfaces.

The overall quality of reception depends greatly on the external components and circuitry used in the builds.   Most serious reviews of the chip-based radios reinforce the judgement that these are suitable only for "casual" listening.  

Google Images of TEF6686-based radios

Google Images of Si47xx-based ATS-3, ATS-20 and ATS-25 radios

The DeepSDR 101 and Clones

The DeepElec DeepSDR 101 is a portable receiver covering 100 kHz to 149 MHz with a spectrum analyzer display that can cover up to 192 kHz centered on the receive frequency.  It can receive CW, USB, LSB, AM and wideband FM.  It uses a Silicon Labs Si5351 quadrature clock generator to an unnamed CODEC used as a Tayloe Zero-IF product detector.   The IQ signal output of the CODEC is processed by a Cortex-M4 CPU.

The DeepSDR advertises an  AM sensitivity of 10 microvolts across the medium wave broadcast band, and 1 microvolt for HF shortwave (0.25 microvolts for SSB/CW).  There is only one processed bandwidth for each mode - 800 Hz for CW, 2.6 kHz for LSB/USB, 9 kHz for Am and 192 kHz for wideband FM.

The DeepSDR 101 clones are sensitive, and the advertised bandwidths are sound reasonable.  But the receivers are subject to strong out of band signals and images, as well as artifacts on the spectrum display.  Like the radio-on-a-chip models, an external preselector and step attenuator are almost a prerequisite for decent reception when using an external antenna.

The DeepSDR 101 is no longer in production, as DeepSDR is developing new models.  That has not stopped numerous clone makers from issuing their own very similar versions.  The clones do not support the uploading/modification of either the memory presets or firmware that the authentic DeepSDR supports.  DeepSDR actually warns about the clones in their firmware update documents.  The original DeepSDR uses a BNC connection on the left side; most clones use an SMA connection on the top left.