RTL-SDR Blog V4 1PPM TCXO SMA Software Defined Radio with Dipole Antenna KIT
Great for many applications including scanner radios, with the ability to DECODE DIGITAL EMISSIONS such as DMR and P25, air traffic control, public safety radio, ADSB, AIS, ACARS weather balloons, APRS, NOAA APT weather satellites, radio astronomy, meteor scatter monitoring, DAB, or for use as a low-cost panadapter with a traditional amateur radio rig.
The V4 comes with numerous improvements and changes over the V3 listed below:
Improved HF reception. Now uses a built-in upconverter instead of using a direct sampling circuit. This means no more Nyquist folding of signals around 14.4 MHz, improved sensitivity, and adjustable gain on HF. Like the V3, the lower tuning range remains at 500 kHz, and very strong reception may still require front-end attenuation/filtering.
Improved filtering. The V4 uses the R828D tuner chip, which has three inputs. We triple the SMA input into three bands, HF, VHF, and UHF. This provides some isolation between the three bands, meaning out-of-band interference from strong broadcast stations is less likely to cause desensitization or imaging.
Improved filtering x2. In addition to the triplex, we are also using the open-drain pin on the R828D, which allows us to add simple notch filters for common interference bands like AM broadcast, FM broadcast, and DAB bands. These only attenuate by a few dB, but can still help.
Improved phase noise on strong signals. Thanks to the improved power supply design, phase noise resulting from power supply noise has been greatly reduced.
Less heat. Thanks to the improved power supply design, the V4 uses slightly less current and generates slightly less heat than the V3.
There are a few other minor changes including a new bias tee LED and a small hole in the case so that it's easy to tell when the bias tee is on.
