Listen to DRM Digital Radio Broadcasts on MW and SW.
Some tips and hints how to use the Newstar DR111.
 
NEWSTAR DR111

MEASUREMENTS,
IMPROVEMENTS
AND HINTS

AM SENSITIVITY
AM SELECTIVITY
SPURIOUS RESPONSE
AM AGC

VOLUME CONTROL

S-METER

AM AUDIO RESPONSE
FM AUDIO RESPONSE
DRM AUDIO RESPONSE

THE AC ADAPTER

POWER CONSUMPTION
(FACTORY VERSION)

POWER CONSUMPTION
(MODIFIED VERSION)

EXTERNAL ANTENNA
PERFORMANCE
AN ACTIVE ANTENNA


LOGGING DRM

12 KHZ IF OUTPUT

FIRMWARE UPGRADE
FIRMWARE V790

DISCLAIMER

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CHENGDU NEWSTAR DR111

The Newstar DR111
Fig. 1
The DR111 is neat and small
 

The Newstar DR111 arrived here by the Swiss Post via FedEx, well packed in a DHL plastic bag and in good condition. I paid USD 120.- for the radio and USD 45.- for the transportation from Hong-Kong. On top of that FedEx presented a bill where they charged me a total of EUR 27.41 in VAT, their handling and import duty - 1.5 kg from China cost EUR 0.71!

The DR111 is 275mm wide, 90 mm deep, 115 mm high and weighs 825 gram. The controls are rather self-explanatory and you soon get used to the operation. The only draw-back is that the clocking of the pushbuttons seem to be a bit on the slow side, so one needs to pause when pushing the same button repeatedly (when setting the frequency). It would have been nice to have an oldfashioned volume control instead of the step function. Especially the step from the first to the second level could have been divided into three, as the increase in volume is too much. Especially if you are using the DR111 on a bedside table you feel the difference.

The telescopic antenna is used mainly (?) for the Short Wave and FM reception. For Long- and Medium Wave there are two separate Ferrite Antennas built into the set. An AC/DC Power Supply with 5 Volt output is used to run the DR111 off the Mains. There are no built-in batteries in the radio, so it cannot used as a portable set.

It has now been playing DRM fairly well for a while, both on medium- and on short-wave. However, the scan function on DRM leaves a lot to wish for as you'll be lucky if it stops on a DRM TX at all. Mind you, this morning it did stop on BBC on 7355 kHz and yesterday it managed to halt on REE on 13720 kHz. Just for my curiosity, I pressed scan half an hour into the TDP transmission on 6015 kHz and during the last 30 minutes the DR111 did NOT stop again before the transmission was over - despite a solid RF signal here 470 km away from the TX.

 

SOME MEASUREMENTS ON RECEPTION AND AUDIO QUALITY


Receiver sensitivity on AM.
The sensitivity was measured by connecting a signal generator to the External Antenna connector. The signal Generator was set to 60% AM modulation and the level was adjusted for 20 dB SINAD reading. The sensitivity of the DR111 in AM mode is very good over the entire AM tuning range.
 

Sensitivity for 20 dB SINAD

Fig. 2

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The S-Meter behaviour from 150 kHz to 27 MHz
The graph below shows the RF Input Level in µV which is needed to light up 1 segment and 3 segments in the S-Meter display.
 

S-Meter behaviour

Fig. 3

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Volume Control Characteristics
The volume control is not continous, but consists of 17 steps where the Step 0 is quiet. The last steps down to zero show an abrupt decrease in the speaker output. It would have been better to have smoother steps at low levels and the larger steps towards maximum volume.
 

Speaker Volume behaviour

Fig. 4

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A close-up plot of the last four steps of the volume control shows the steep fall towards zero volume. It would have been better to have had a smoother ending.

In the meantime the manufacturer told me on 1st June2012 that they will adjust this issue in the next firmware release.
 

Speaker Volume behaviour

Fig. 5

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The volume control in the latest firmware version 723 from July 2012 has been changed from 17 to 39 steps. The result is much better than in the previous version. Now you can put it on the bed-side table an turn the volume down very low.
 

Fig. 6

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AM Adjacent Channel Selectivity

The Selectivity was measured at 11830 kHz with 50 µV RF Input level in 50 Ohm and modulated with 1000 Hz, 60% AM. The signal generator was adjusted in 1 kHz steps up and down from the receiver frequency and the AF output was measured in dB relative to the center frequency. Three measurements were done with 1 kHz (yellow), 5 kHz (red) and 6 kHz (blue) kHz IF bandwidth.
 

Adjacent Channel Selectivity in AM Mode

Fig. 7

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Unwanted spurious response on AM

The signal generator was tuned to 20000 kHz and its output level was adjusted to +80, +60 and +55 dBuV respectively. An AM scan was performed for each input level. On 21640 kHz a tone was heard in the loudspeaker. On the other frequencies listed below the DR111 stopped scanning, but nothing was heard in the speaker. There are no data available for IF frequency and no information on whether the receiver is a single or double conversion superheterodyne. The results are shown in the table below:
 

Unwanted +80 dBV Unwanted +60 dBV Unwanted +55 dBV Notes
6000 kHz      
9520 kHz      
9775 kHz      
15200 kHz 15200 kHz    
19100 kHz 19100 kHz    
21640 kHz 21640 kHz 21640 kHz Sine wave
25640 kHz 25640 kHz 25640 kHz Question mark
26000 kHz 26000 kHz 26000 kHz Question mark

Fig. 8

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Automatic Gain Control in AM Mode

The graph below was plotted at 1296 kHz on Medium Wave. An abrupt increase in the RF input level causes the DR111 to reduce (IF?) gain in steps. This can be heard in the loudspeaker. The audio output in the speakers is fairly constant at RF levels above 1.5 µV. Below 1.5 µV the audio output decreases rapidly. There is no noise att all in the loudspeakers in absence of a signal or at very low RF signal levels.
 

AGC, AM Mode

Fig. 9

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AM Audio Response

The Audio Response was measured by setting the signal generator to 60% AM modulation and the modulation frequency was measured from 100 Hz to 6000 Hz. Two series of measurements were done, one with 6 kHz IF bandwidth (blue curve) and the second with 4 kHz IF bandwidth (red curve). The result is shown in the graph below.
 

Audio Response in AM Mode

Fig. 10

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FM Audio Response

In a previous test (with the Morphy Richards radio) I took my old ITT Schaub Lorenz Touring T60 from the 1960's as a reference receiver. The Schaub Lorenz sounds very pleasant on FM. I compared this radio with the AF output from the DR111. The audio frequency response in the Schaub Lorenz is rather linear from 100 Hz to around 20 kHz. Doing the same test with the DR111 shows a better audio frequency response compared to the Morphy but it could be better. Above 4000 Hz the Newstar DR111 has a roll-off of 20 dB / octave which leaves little output of the higher frequencies. Still, when listening to an FM station, the sound is not that bad anyway.
 

FM Audio Response compared to Schaub Lorentz Touring T60

Fig. 11

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The Audio Frequency response in DRM mode

 
The Dream Software can operate as a DRM Transmitter. This, in connection with my signal generator Schlumberger Stabilock 4040 created a DRM Short Wave Transmitter, that was at least good enough for testing the DR111. I tuned the signal Generator to 7988 kHz. The generator was modulated in AM mode with the output from Dream set to TX Mode B, 16-QAM / 64-QAM, Protection level 1 und Long Interleaving. The modulation level was around 35%. In this configuration the DR111 frequency response was about +5 dB/octave linear from 1000 Hz to 6000 Hz. Above 6.2 kHz is practically nothing recordable. This is most likely a limit due to the Dream TX configuration.

Looking at the output from the signal generator on a HP Spectrum Analyzer the sidebands with the DRM 12 kHz were clearly visible. The DR111 was tuned to 8000 kHz. The output level from the signal generator was set to -47 dBm (1 mV in 50 Ohm).

I made the measurements in the Earphone output jack (3.5 mm Jack). The result was positive. The frequency response is not linear. But the reception of DRM signals is still loud and clear.
 

DRM Audio Response

Fig. 12

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Power Consumption with the 5 Volt DC adapter (original design)

State Current Power Notes
Switched on 340 mA 1.87 Watt Backlighting ON
Switched on 330 mA 1.82 Watt Backlighting OFF
Stand-By 310 mA 1.71 Watt  
Fig. 13

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The DANGER of connecting anything else than the 5 Volt DC Power Supply!

After an accidental 12 V DC input to the DC jack on DR111 it instantly short-circuited and died a sudden death. Nothing to do but to destroy the guarantee seal and remove 8 screws and open the radio to find out what had happened. A diode marked on the PCB as "ZD1" or "201" had broken down - it seems this was a Zener Diode connected in parallel to the DC socket. This explains why the current rose dramatically during tests with a regulated DC Power supply when the supply voltage was adjusted slightly over 5.5 V DC. DANGER!!
Insert a 7805 voltage regulator to avoid trouble

Fig. 14

I removed the DC socket from the printed circuit board, bent its PLUS solder lug upwards so it was not in contact with the input voltage connection any longer and soldered the DC jack back onto the DR111 printed circuit board. In the hole where the 5 Volt lug was connected before I wired a piece of yellow lead wire to connect to the output of a 7805 voltage regulator. Then I soldered a short red wire to the plus lug on the DC jack and put a shrink tube over the solder joint to prevent a short-circuit to ground. There is not much space between the DC jack and the shield case containing the radio parts.

Next I soldered the 7805 three-pin regulator to the shield case near the DC jack and wired a 4.7 F/25V on the input pin to ground and a 22 F/16V on the output pin to ground. Finally the red wire was soldered to the input pin of the 7805 and the yellow wire was soldered to its output. The DR111 now needs an AC/DC Mains Adapter with an output of at least 9 V (minimum current capacity of 0.5 A) instead of the original adapter's 5 V DC. The power supply must be capable of delivering at least 500 mA, otherwise the DR111 might re-boot during power up. Interestingly, after this modifiaction, the total power consumption of the radio became lower than before.


Power Consumption with the modified DC input 

State Current Power Notes
Switched on 250 mA 1.25 Watt Backlighting ON
Switched on 240 mA 1.25 Watt Backlighting OFF
Stand-By 195 mA 0.98 Watt  

Fig. 15

I don't understand why Chengdu Newstar used the "Stand-By" function as an ON/OFF switch. When the DR111 is "switched off" it consumes almost as much power as if it is switched on. It would have been better to provide a switch on the set that cuts the power supply entirely. After all we want to save energy. True, when a main swicth is used, the DR111 needs to boot up, but that doesn't take that long anyway.

 

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The reception with the Telescopic antenna compared to an External Antenna

The sensitivity in AM Mode measured with a signal generator (I can only measure sensitivity on AM) is in fact not that bad - at least if you look at Fig. 2 a bit up on this page. But with no documentation or schematics available, it is hard to say why the performance on the telescopic antenna - to my liking - is a bit weak. When I switched to my roof-top active antenna I got much better reception.

Before I connected anything to the external antenna jack I checked if it was resistive or not. It was. I checked the value, and it was about 1.4 Mohms. Therfore I am feeding the active antenna to the DR111 with a capacitor in series, not to let any 12 Volts DC from the antenna's coax cable into the front end of the DR111.

I recorded some data for 9780 kHz (REE) on the internal telescopic antenna and on my modified PA0RDT active antenna. I got one to two S-Meter segments lighting (in AM mode) on the internal antenna with 19-21 dB SNR on DRM, compared to 3-4 S-Meter segments (in AM mode) with the active antenna with 24-25 dB SNR on DRM. That is a >20 dB (factor >100 at least) difference. The REE signal is pretty strong here in Switzerland - about 0.6-1 mV / 50 Ohm. On the FRG-7700 the SNR was around 27-28 dB.

A little later on 9850 kHz (RUVR) I got more or less only 0 (zero) S-Meter segments (not) lighting (in AM mode) on the internal antenna with 21-22 dB SNR on DRM, compared to a steady 2 S-Meter segments (in AM mode) with the active antenna with 25-26 dB SNR on DRM. That is a considerable difference too. The RUVR signal was not so strong - about 0.1 - 0.11 mV / 50 Ohm. On the FRG-7700 the SNR was around 30 dB.

I did another test with the DR111 connected to two signal generators, one on 6175 kHz and the other on 7545 kHz. With a -50 dBm signal from both I got an audible, rather strong signal on f1 + f2 = 13720 kHz in the DR111. -50 dBm is about 0.7 mV in 50 Ohms. It is hard to say whether this could be a problem in DRM if there are strong stations on unfortunate frequencies which adds or subtracts interfere with the DRM frequency.

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Tuning the bands and reception results

Since the new firmware V790 was published in the beginning of August 2012, the DR111 became much more pleasant to use. The muting of the AF when tuning either with the tuning knob or with the up/down buttons was removed. Now you can tune the bands in AM and FM and hear what you are tuning into. I got another DR111 so I can compare the performance between the two, and I found out that the second receiver works much better on Long Wave and Medium Wave than the first receiver did - or does. I modified my first receiver so instead of the ferrite antennas I use the telescopic antenna instead. To be honest, my first receiver got part of my modified PA0RDT Active Antenna built into it and this modification makes the DR111 even more sensitive on Short Wave.

Lately I have monitored several DRM transmitters using only the built-in telescopic antenna. The reception is great on both receivers. Up to this date I have uploaded about a hundred logs on my Twitter page. Go to Twitter an look for @TerjeIsberg and see for yourself.


Adding an Active Antenna to the Telescopic Antenna

Adding a part of my modified PA0RDT Active Antenna into the DR111 makes the DR111 even more sensitive on Short Wave. A significant improvement on both AM and DRM was achieved with this modification.

The high input impedance of the tuner in the DR111 eliminates the need for the emitter follower in the active antenna. The internal supply voltage is 5 Volts, so some resistor values needed to be changed. I mounted the components on a small printed circuit board near the ferrite antennas.

The yellow wire in the picture below is connected to the telescopic antenna, the white wire goes to the Short Wave tuner, the red wire is +5 Volts and the blue wire is connected to DR111 ground (0V). The printed circuit board is double-sided. The rear side is used as a ground plane for best RF stability.

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Active Antenna in the DR111  

Fig. 16

 

Active Antenna in the DR111

Fig. 17

The "Half" Active antenna built into the DR111

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Logging DRM broadcasts

If you want to make DRM logs, be sure to set the DR111 clock to UTC. That is the time that will be written to the memory card in the DR111.

The DRM reception logging function records various data during a DRM session. To enable the logging function, first create a folder with the name "drm_log" (without quotes) in the root directory on a SD card. The DR111 will recognize this folder and create reception logs under this folder automatically. Reception log can be plotted with the DRM Log Plotter. The DR111 can only handle SD cards with 8 GB or less capacity.

To log a DRM transmission, do like this:

  • Switch on the DR111 and tune in to a DRM transmission
  • When you hear the sound in the DR111 speakers, insert the SD card into the slot
  • At the end of the DRM transmission, be sure to switch the DR111 to Stand-By.
  • In Stand-By, remove the SD card and store it or insert it into the computer's card reader to evaluate the log.
Never pull out the SD card when the DR111 is on a DRM TX when there is a directory "drm_log" on the SD Card. Switch the DR111 to stand-by first, then remove the card. Otherwise the SD Card goes to SD Card Heaven.

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How to add a 12 kHz IF output to the DR111 for different purposes

How does this receiver work? Just out of interest I checked all the pins on the connector of the radio module set to DRM mode with an oscilloscope probe. To my surprise I found an AC signal in the outer row on pin 4 from the left. The pin has DC voltage on it, so I connected an isolation transformer via a 1 uF capacitor to avoid current or short circuits. There is 12 kHz (or about 11.4 kHz) signal present both in AM and DRM, so it doesn't matter which mode the DR111 is set to operate in. The signal is sufficient to feed to the Line Input of the computer.

 
Location of the 12 kHz IF output in the DR111  

Fig. 18

The isolation transformer was simply soldered to the shield cover of the radio unit. The 12 kHz earphone jack is seen to the right in the picture below. The advantages in DRM are that your DReaM logs will get the correct time instead of the unstable time stamps provided by the DR111 and there are no time lag when logging for several hours. Another advantage is that it is possible to search the bands in AM mode for DRM signals. In AM mode you can monitor what you receive in the loudspeaker of the DR111 which is not possible in DRM when the speaker is silent until a decoded DRM signal is present.

Another advantage in AM mode is that you can use the DReaM in analog mode and profit from the different receive modes (AM, LSB, USB, CW, FM) and filter bandwidth settings. The DReaM version 2.1.1 also has a powerful noise reduction tool which makes a big difference in listening to short wave.

 
The isolation transformer and the 12 kHz IF output socket  

Fig. 19

 
The schematic diagram for the 12 kHz IF output  

Fig. 20

In case you wonder what are the components in front of the active antenna board, those are two smooth operating push switches which I use for adjusting the DR111 frequency up and down instead of the two TACT switches in the middle of all the switches on the top.

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How to load a new firmware to the DR111
1 . What you need if you want to load a new firmware:
  • The ZIP file with the new Firmware
  • One SD/SDHC Card (8GB or less capacity)
  • A computer
  • Your DR111 Receiver

2. Prepare the SD card and the Firmware files:

  • Unzip the Firmware file to a temporary directory. You will find three files named Part1, Part2 and Part3
  • Insert an SD/SDHC card into the computer and format the SD/SDHC card to FAT or FAT32 format (if it is not already formatted)
  • Copy the three files part1, part2 and part3 of the firmware to the root directory of the SD card
  • Remove (eject) the SD/SDHC card safely from the computer.
3. Step by step instructions to upgrade:
  • Power off the receiver by pulling out the DC plug from the DR111
  • Insert the SD/SDHC card with the firmware files into DR111 SD card slot.
  • Power on the receiver by inserting the DC plug to the DR111
  • The loading of the new firmware will start automatically. The update files will be verified and then the update follows. At the end a message "update finish, please reboot" is displayed.
  • Now, power off the receiver by pulling out the DC plug from the DR111
  • Remove the SD card from the DR111 SD card slot and wait 10 seconds, then
  • Reboot the receiver by inserting the DC plug to the DR111. The DR111 will light up and the new firmware is active.
IMPORTANT NOTICE:
Do not turn off the power during the upgrade procedure, otherwise the receiver might be damaged!

You will also notice that you have lost all your preset stations and you have to set the clock and the date etc. all over again.

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Download the firmware V790 here:

Download the zip file and save it in a temporary folder. Unzip the files and follow the instructions above under "How to load a new firmware to the DR111".



Disclaimer:
You agree to update the firmware in your DR111 at your own risk. Although I had no problems whatsoever upgrading my DR111 with the V790 and other versions of the firmware for various test purposes, I or Hobbyradio will not be held responsible if the update for some reason should fail, or if the DR111 for any reason should not work properly or at all after the upgrade.

You also agree to that if you decide to make any of the modifications described in this article, you do it at your own risk.

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Latest edit: 14th March 2016