The IC-7851 incorporates two completely independent receivers, from the antenna inputs all the way through to the stereo headphone and individual external speaker outputs. All the performance of the first receiver is duplicated for a perfectly matched set of “Twins”. When connected to external stereo headphone, main and sub receiver audio can be mixed or separated to the right and left.

RTTY, PSK31 as well as the new PSK63 modes are available at your finger tips without the use of a computer. The built-in Modulator/Demodulators are activated by via the radio's functions buttons or an optional USB keyboard. TX memories make contacts a snap and communications logs can be stored on an SD memory card.

“Build your own” IF filters by adjusting the IF filter width, 50-3600 Hz, as well as soft or sharp filter characteristics for your perfect sound. Save these settings in three userdefined filter presets, Wide/Mid/Narrow, by mode to give you full customization of your filters.

HF operators marvel at how well DSP reduces interfering signals and noise. Signals such as heterodynes and AM Carriers can be eliminated with automatic notch filter technology.
Making interference from RF sources such as beat signals and RTTY signals is a thing
of the past. Additionally, the filter shape of the manual notch can be adjusted in three steps – with more than 70dB of attenuation!

Manual Notch Filter Characteristics

Once the IF filters have been “tweaked,” the operator has additional control with the digital twin passband tuning (PBT). The digital twin PBT allows flexibility of both the IF shift and narrowing of the digital IF passband by moving the IF passband. With the digital IF filters, PBT performance allows you to cut away all the interference and noise to hear the actual signal.

The digital noise reduction separates a target signal from noise components and noise suppression level is variable in 16 -steps, depending on the noise level. The low latency digital noise reduction is achieved by applying an adaptive filter using the high speed DSP computing power.

While most noise blanker reduces pulse type noise, the IC-7851 introduces a new automatic digital noise blanker circuit. While using the 15/9/6kHz roofing filters, the digital noise blanker gives you full control. When the 1.2kHz Optimum Roofing Filter is activated, the best blanking level is automatically selected. Additional adjustments allow you to tweak the threshold level, blank time and attenuation level parameters.

With the flexibility of DSP-based waveform shaping, transmit and receive audio quality is adjustable to suit your preference. Three user-adjustable transmit filters, Wide/Mid/Narrow, allow you to set both the low and high cut-off frequency limits. (100, 200, 300, 500Hz for lower and 2500, 2700, 2800, 2900Hz for higher frequencies.) In addition to the TBW filter, the IC-7851 has an equalizer to digitally tweaks your transmit audio with separate bass and treble controls (11 steps each for bass and treble). The receive audio can be tailored with modespecific Bass/Treble or audio passband settings.

The DSP controlled RF speech compressor provides additional punch while maintaining the original tone quality of the operator. The IC-7851 utilizes the 32-bit DSP for the RF speech compressor, providing the maximum punch without the fuzzy sound. It's great for breaking through the noise and hash to complete the QSO.