Atom CPUs was created for office applications and web-browsing, not for signal processing. Atom-based computers may work, but performance will be severely degraded.

Probably your Firewall or other antivirus software blocks data exchange between PC and the radio. Short data exchanges do pass through, like SDR info, but large pieces of data are considered a threat. Add ExpertSDR2 software to the exceptions list in your antivirus software.

Answer: 

Currently, all our devices have one ADC and ExpertSDR2 software support two independent software receivers. Each receiver (RX) has its own separate panorama, set of settings, and can use different modes. Each RX has its own independent CAT interface and VAC. The second RX can be viewed in a separate window on the second monitor.

Answer: 

The maximum panoramic resolution requires a lot of CPU resources. Not all PCs are able to process all data, so this leads to the sound issues.
We recommend lowering panorama resolution if at higher sample rates your PC has sound issues.

Answer: 

DIGL/DIGU modes are identical to LSB/USB, the only difference is that tuning frequency is shifted by the offset value relative to 0 Hz by LF. User can manually set this value in Options-> Device-> TX-> DIGL/DIGU-> offset.
It was done for comfortable tuning on digital stations by the mouse click on the ExpertSDR2 panorama.

Answer: 

The S-Meter shows the signal level in the RX filter bandwidth.

When no antenna is connected, the S-Meter shows the level of the radio's internal noises.

The readings depend on the filter bandwidth, if you set SSB mode with 3 kHz bandwidth, the readings will be at the higher level, if you set CW with 100 Hz bandwidth, the S-Meter readings will be lower.

The radio's internal noises also depend on the Preamp level (sensitivity). If you set -20 dB ATT, the sensitivity will be at its worst and S-Meter readings higher, if you set Preamp +10 dB, the sensitivity will be higher and radio's own noises will be at its lowest.

S-Meter in the ExpertSDR2 has two different calibrations for HF (0-30 MHz) and VHF (30-300 MHz).

HF and VHF signals with the same dBm level have different S-scale values.

You can find calibrations tables for HF (table 3) and VHF (table 4) at the following link http://hamwaves.com/decibel/en/

For example:

29 MHz -127 dBm ~ S0.5 (preamp on)

52 MHz -127 dBm ~ S3.5 (preamp on)

To verify you may connect a signal generator to an antenna port and compare the generator signal with the S-Meter readings for all S-levels, compare to tables from the link above.

Also, you can see the IARU recommendations for HF and VHF S-Meter calibration at the following link https://en.wikipedia.org/wiki/S_meter
For HF S9 = -73 dBm = 50 uV (50 Ohm), for VHF S9 = -93 dBm = 5 uV (50 Ohm).

S-Meter in the ExpertSDR2 corresponds to the IARU recommendations, each device is calibrated at the factory during manufacturing.

Answer: 

The ExpertSDR2 software separates the radio signal of the DRM station, then pass it to the third-party software (Dream DRM, WIN DRM etc.) for decoding via VAC (Virtual Audio Cable).

Answer: 

Bandscope has its own DDC software receiver in the radio's hardware, it works in parallel with the main receiver.

Answer: 

1. Noise level on the spectrum scope depends on its resolution. Divide panorama sample rate (in Hz) by the FFT size (in the Spectrum settings) you'll get the minimum FFT bin band - let's call it "single-unit filter". The whole panorama consists of such single-unit filters. Each such filter displays resulted power in its own band and this power is displayed as a point on the panorama. Spectrum line is drawn based on this points. If there is a strong useful signal, with high signal-to-noise ratio, inside the single-unit filter, then panorama and S-meter readings will be the same. As a rule, it applies to monochrome and/or narrowband signals like CW or PSK, e.g. someone's tone signal. If there are no useful signals, then will be displayed еру noise power in the filter bandwidth.

2. S-meter displays summed signal power in the filter bandwidth. i.e. a sum of useful signal and noises in the bandwidth.

Sample rate 156250 Hz. FFT size 16384 (max). SSB filter bandwidth 2.9 kHz, noise level on panorama -118 dBm. Receiever receives air noise.

Task: calculate S-meter readings.

Step 1. Let's calculate FFT bin band (single-unit filter). 156250/16384 = 9,53 Hz. This is the bandwidth of a single-unit filter.

Step 2. Let's calculate the difference between RX filter bandwidth and single-unit filter. 2900Гц/9,53 Hz = 304 (times). Filer bandwidth is approximately 304 times wider than a single-unit filter.

Step 3. Let's calculate the difference in dB between summed noise power in single-unit filter bandwidth and summed noise power in RX filter bandwidth. 10*log(304) = 24.8 dB. i.e. noise power in 2.9 kHz bandwidth will be higher than in single-unit filter on 24.8 dB.

Step 4. Let's calculate S-meter readings. -118 dBm + 24,8 dB = -93,2 dBm.

Approximate S-meter readings will be -93.2 dBm.

Conclusion: as you see, the calculated value of the S-meter readings is equal to real readings on the screenshot. The difference is 1 dB, it could be explained by the fact that the noise level slightly differs from -118 dBm, we assumed from the screenshot.

If there is a useful signal in the RX filter bandwidth, e.g. SSB signal, S-meter will also display the summed power of all voice components in the filter bandwidth. On panorama, each separate voice component will be displayed lower than overall S-meter readings. This statement is also valid for TX mode.

Answer: 

S-meter values and audio level have program compensation when you use the attenuator because signal level on the antenna input is always the same and doesn't depend on the attenuator level. With this solution, a user doesn't need to calculate real values on his own, every time when the -20-dB attenuator is used. Also, he doesn't need to adjust AF or RF level every time when the -20-dB attenuator is used, like in most classic transceivers.

Attenuator influences only receiving dynamic range, S-meter and audio level stay the same. If you disconnect antenna you can see how receiver’s noises are changing when you switch the ATT. Receiver's noise level is lower when you select ATT 0 dB, it means that RX sensitivity is higher. When you select ATT -20 dB, it means that RX noise level is higher, but RX sensitivity is worse. It is done in the hardware.

Answer: 

When you operate in DIGI modes you need to carefully adjust VAC gain. In this case you need to adjust VAC gain for TX mode (Options-> Device-> VAC-> Receiver1(2)-> TX Gain). Also, we recommend to set Mic level indicator and control the signal level. DIGI modes signal should be around -3...-1 dB.

Note: TX Gain parameter might be either negative or positive, depending on whether you want to amplify VAC signal or attenuate it.

Answer: 

Transceivers are supposed to operate with loads around 50 Ohm impedance. This is one of the main requirements.
From our experience, antenna SWR may rise up to 4...5 for RX mode without a significant drop in receive quality. For TX we do not recommend to go above SWR 1.7...2.

Answer: 

For X8 switch to work properly, enable the РА button in the ExpertSDR2 software.

Answer: 

You hear HF crosstalks of the transceiver on the PHONES jack and crosstalks detected on nonlinearity of the schematic. Try to use ferrite beads with transparency 1000-4000 on the coax cable of the antenna and Mic cable. Make 5-10 winds of cable around the bead.
As a rule, this effect happens because of HF current on the cable surface (instead of inwards). This crosstalks also may cause feeding of an external PA, so they should be eliminated.

Answer: 

No, MB1 has two software receivers, but one ADC, you can use both receivers work either on 0...80 MHz or 80...160 MHz.

Answer: 

You can transmit on the 4M band via low power output (DAC OUT), max 10mW. To get more power you can use an external power amplifier. To RX on this band use direct input/output of high-speed ADC/DAC. For comfortable RX operation connect a narrow pass filter to the RX IN. If necessary use an external RF amplifier.

Also, the transceiver can operate on the LW band. To receive signals above 9 kHz you can use antenna connectors A1, А2, A3, and А4. For TX use DAC OUT, because the internal HF power amplifier doesn't work on these frequencies.

High-speed ADC in MB1 simultaneously receives several Nyquist zones, 0-80 MHz, and 80-160 MHz. Signals from different Nyquist zones overlay each other as image channels. For example, 15 MHz on HF is reflected on 145 MHz. For ADC to avoid HF stations when operating on VHF, we installed SAW filter with pass frequencies 144-148 MHz. Also, there is another VHF wideRX bandpass filter: 95-155 MHz (Butterworth - 5 Order) for the whole 2nd Nyquist zone.

VHF SAW filters final attenuation for HF frequencies is around -60-70 dB. For example, there is an S-9 station on the 20M band, you'll see it on VHF as an S-1 station or lower. If you want to completely attenuate HF stations, you can install the additional HPF we manufacture for the MB1, with 100 MHz cut frequency. From our experience, HF stations can be received on VHF 6-15 dB above the noise floor, depending on the VHF antenna quality. Good VHF antenna is an additional band filter. If you'll receive VHF stations on unmatched HF antenna (as an experiment), you'll see that AFC of the internal filter will be corrupted and attenuation of HF stations worsened.

Answer: 

There are two ways to connect an external speaker to the MB1:

1) Connect a multimedia speaker via adapter jack 3.5-6.3 to the PHONES jack on the front panel.

2) Connect a multimedia speaker to the headphone jack 3.5 on the rear panel, then open: Options-> Sound card-> Output list (first in the list). Set the Enable check box, now you can listen to the sound from a multimedia speaker.

Being the software defined radio, there is no provision for hardware generated FSK in the MB1, but from our users' experience, AFSK is better in so many ways including decoding ability, seeing bad activity and so on. When you use DIGI software in the MB1 and make a virtual audio connection, the quality of TX signal the same as in FSK.

We would recommend simplifying data operation by using the MB1's own computer for hosting the RTTY software. Also, you may run the RTTY software on the external PC and use a mic (input) and a line (output) on the rear panel to get the AFSK audio into the MB1.

Nominal (PEP) HF output power of the MB1 is 100 W, in SSB mode it might differ from 30 W up to 80 W, depending on the compressor and clipper settings.

Yes, the MB1 has internal protection, output power is automatically decreased if SWR exceeds the manually set in the ExpertSDR2 value 2-5.

Yes, you can. Ext CTRL switches in the MB1 are open collectors and can give you either open line or shorted to ground lines.

If you want to get TTL level 0V or +5V (+12V), you should tie serial resistors 1-10 kOhm.

When the switch is on - it gives logical "0", when off - logical "1". You can adjust the Ext CTRL table for the required band combination.

If you need 5 V TTL levels, you can use 5V zener diode from each line to GND and put resistors with diodes into Ext CTRL connection box.

Yes, phones and the Mic jacks can be configured for operation in DIGI modes or for voice operations if you use voice macroses from the Log. MB1 uses 2 channels for one receiver, but if you use 2 different receivers (RX1, RX2), you can adjust balance for each receiver, e.g. RX1 for the left channel, RX2 for the right channel. Yes, they are independent of the MIC GAIN and AF OUT knobs, because these inputs/outputs are used in VAC menu and have their own RX and TX gain settings, which can be adjusted by the user.

The Windows gain settings also can be used for gain adjustments, but we recommend to use only ExpertSDR2 gain settings.

*Yes, they are independent of the MIC GAIN and AF OUT knobs because these inputs/outputs are used in VAC menu and have their own RX and TX gain settings, which can be adjusted by the user.

If used VAC menu, TX monitoring doesn't work.

The ExpertSDR2 software has an additional line output menu, where you can select the audio output device e.g. speaker on the front panel. It contains RX/TX signals, normally this menu is used for recording QSOs in contests, but if you need you can use it for other operations.

The rear Mic input is mono, but it is split into two channels.

*Yes, it can. When the PTT signal goes from the PTT footswitch, TX button on the front panel, TX button in the software window - will be used an audio signal from the Mic input (front panel inputs).

Answer: 

To set up independent audio output from the front and rear panels of the MB1 you should:

- Open Realtek HD Audio Manager (in Windows system tray) or open Control Panel\Hardware and Sound\Realtek HD Audio Manager

- Press Device advanced settings

- In Playback Device set Make front and rear output…

- Press OK

For more comfortable use:

- Open Control Panel\Hardware and Sound\Sound

- To rename your connections, press Properties of each connection and rename it to Rear Panel and Front Panel

- This way, with selected MME driver, ExpertSDR2 will detect audio outputs as Rear Panel and Front Panel.

Answer: 

Shut down the MB1, unplug, wait 2 minutes, reconnect. Double check antenna selection and settings.

The top operating temperature is 75 Celsius. When the transceiver will reach this temperature, the special protection will trigger and shut down the transceiver.

If the temperature is below 75 Celsius, it may be considered as normal.

Internal WLAN access point (standard 802.11 n) allows you to setup wireless connection between your transceiver and PC. For example, your transceiver set up at your workstation and switch to WLAN mode. Using a notebook with a built-in WLAN you can work on the air being in another room, or basically anywhere where you can reach this WLAN.

The only thing you need for internal WLAN to work is to connect a miniature antenna supplied with the module to the transceiver, that is the main difference between the internal WLAN module and an external. An external access point is a separate device with power supply and requires a cable connection to the transceiver. From the operational standpoint, both solutions are the same.

You can revert any changes done to the internal access point or transceivers IP address, by pressing the RST (reset) button on the rear panel of the transceiver. Press the RST button, then while holding it on switch on the transceiver, release the RST button. At this moment LED on the front panel of the transceiver will start blinking. You need to wait until LED will stop blinking and turns to constant green. Your transceiver is ready to work.

No, SunSDR2 PRO has two software receivers, but one ADC, so you can use both receivers to operate either on 0...80 MHz or 80...160 MHz.

High-speed ADC in SunSDR2 PRO simultaneously receives several Nyquist zones, 0-80 MHz, and 80-160 MHz. Signals from different Nyquist zones overlay each other as image channels. For example, 15 MHz on HF is reflected on 145 MHz. For ADC to avoid HF stations when operating on VHF, we installed SAW filter with pass frequencies 144-148 MHz. Also, there is another VHF wideRX bandpass filter: 95-155 MHz (Butterworth - 5 Order) for the whole 2nd Nyquist zone.

VHF SAW filters final attenuation for HF frequencies is around -60-70 dB. For example, there is an S-9 station on the 20M band, you'll see it on VHF as an S-1 station or lower. If you want to completely attenuate HF stations, you'll need an additional external narrow band filter. From our experience, HF stations can be received on VHF 6-15 dB above the noise floor, depending on the VHF antenna quality. Good VHF antenna is an additional band filter. If you'll receive VHF stations on unmatched HF antenna (as an experiment), you'll see that AFC of the internal filter will be corrupted and attenuation of HF stations worsened.

The reason for that is peak-factor, it equals 3 for voice signals. TONE signals have constant output power 20 W. Voice signals with peak power of 20 W have real power approximately 3 times lower. To increase the real power of voice signals use the compressor and other features in the TX processing module.

We can recommend a power supply with +15V DC voltage and 5A current. A power supply can be either transformer or impulse.
If you prefer impulse power supply, you need to pay attention to filtering of the output voltage and presence of the filtering paths on the 220V line. It's common when distortions are created via 220V line. A power supply creates distortion and wiring act as an antenna. Filtering paths are mandatory, also we recommend to install ferrite beads on both ends of the power supply cable.

Max signal level on the receiver's input is (enabled АТТ -20dB) ~S9+100dB on the S-meter scale, which is approximately 4.5V of HF voltage peak-to-peak. A 1000W station may be in 10-20 meters from you and receiver will still function properly.

SunSDR2 PRO and ExpertSDR2 have two independent software RXs, which can be used by one or two operators.

Basically yes, the 1st operator can receive and the 2nd operator can transmit, but to do that we should implement the Duplex mode.

The current hardware of the SunSDR2 PRO supports Duplex mode.

When you transmit one antenna connector (A2 or A3) can be used for RX and another one for TX, either on one band or on different bands.

At this point, the Duplex is not supported, while you transmit on the 2nd RX, receiving on the 1st RX will be blocked.

You can use any PA which requires input power below 20W.

SunSDR2 PRO supports max output power correction for operation with external PAs.

It means that you can set max output power in SunSDR2 PRO, e.g. 8W and can adjust the Drive level from 0 to 100%, output power will be adjusted from 0 to 8W (not to 20W). This way you cannot damage your PA by overload on the PA input.

We can recommend HLA-150 Plus or 300 Plus.

In Tone mode, with 2% on Tone slider:

On HF (14MHz) min output power ~ 4.4 mW.

On VHF (145.5 MHz) min output power ~ 0.5 mW.

Yes, it has an automatic protection of the internal PA. In parallel to each antenna connector there is a 2W 1kOhm resistor, to remove slowly accumulating static discharges in the receiver, and also to provide an SWR=20 in case of antenna disconnect.

HF/VHF output stages can operate with high mismatches, up to SWR=20, but at the same time, they get warmer. Output stages can easily endure short mismatches.

To TX you'll have to make some tweaks with ESDR2.
Via low power output (DAC OUT) you can transmit on - 0.1kHz - 150MHz max 10mW.
BUT:
- If you try to transmit on these frequencies internal power amplifier can be damaged by this operation.
- Harmonics may appear while transmitting out of amateur bands.
- I have to mention that, we can not guarantee the proper functioning of our devices with changed parameters and we are not responsible for the customers transmitting on the frequencies out of HAM range, this could be done only with the proper license.

To RX on these frequencies, we'll recommend to us the ADC IN because standard antenna inputs will have low sensitivity.
Maximum allowed signal level on the ADC IN connector is 0.3V of the active voltage (RMS). Do not exceed it, it may result in the transceivers overload and ADC fatal damage.

ADC cannot receive DC, receiving available from 9 kHz and higher, never tested below 9 kHz.
RX below 100 kHz will have low sensitivity, we've never tested our devices on these frequencies.

Press the L/W button once again and wait until the LED turns green.

Yes, you can use a straight key, to do that, you should disable the Break-In in the ExpertSDR2 and use one of the contacts of the KEY jack, page 11 - https://eesdr.com/images/Document/SunSDR2_PRO/SunSDR2_PRO_Hardware_Manual_v1.2.pdf.

LED blinks - it means the transceiver is initializing and not ready for operation. If it constantly blinks, it means there is no network connection.

Answer: 

The normal operating temperature is +45...+55 C because the ADC is using the casing as a heat sink.

Answer: 

ColibriNANO connected to RPI3 (with our image) via USB connector, RPI3 connected to a router via LAN.

RPi3 will automatically get the IP address from a router. You'll need to set up port forwarding (5050 by default for the ExpertRS and 80 if you want to remotely control the receiver via WEB-client) from a router into RPI3 IP address, you can find the example in Paragraph#3 in the User Manual for the ExpertRemote system. Now you can use remote control.

Answer: 

1) Connect the ColibriDDC to your PC with Ethernet cable.

2) Connect the ColibriDDC to your transceiver via CAT-system in the ExpertSDR2, using the OmniRig (Options-> CAT-> Interface-> OmniRig).

You should have installed OmniRig SW on your PC.

3) In the OmniRig settings (in the ESDR2) set the Enable checkbox.

4) Press the Configure button to open the OmniRig SW settings window.

5) All further information you can find in the User Manual-> CAT Menu.
Then you set up the OmniRig to operate with a certain transceiver via a certain COM-port.

Answer: 

High-speed ADC in the ColibriDDC can receive signals in 0-800 MHz range, but this range is divided into special Nyquist zones. The Nyquist zone bandwidth is 62.5 MHz. ColibriDDC can receive only in one Nyquist zone at the same time e.g. 0-62.5 MHz, 62.5-125 MHz, 125-187.5 MHz etc.

For each zone, you should use BPF, for the 1st Nyquist zone ColibriDDC has its own Low Pass Filter 0-60 MHz (Chebyshev I - 7 Order).