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CC1200DK: How to know the energy level which being around the test place?

Kwangbog Ham
Intellectual 390 points
Part Number: CC1200DK
Other Parts Discussed in Thread: CC1200

Dear Sir,

Thank you for your response and advices.

We had finished the Line-of-site in similar urban area(plz, refer to the below picture) and then, there are some questions.

Anyway, our test condition are:

(Transmitter status)

1. Height: 1m above ground.

2. Transmit RF output power: 10dBm

3. Antenna gain: 2dBi which is included in CC1200DK

(Receiver status)

1. Height: 7m above ground.

2. Antenna gain: 2dBi which is included in CC1200DK

(Common setting)

- 802.15.4g compiant mode on SmartRF studio program, other parameters are default.

- Frequency: 866MHz, 868MHz

- As you have guided me to measure the sensitivity, we had check the sensitivity(-108dBm @ 50kbps) with SMU measurement device.

- This sensitivity is simiar with value on CC1200 datasheet.

(Result)

- Communication distance between transmitter and reciver is about 700m (condition: PER < 1%)

- Status on SmartRF studio:

+ Average RSSI: -74.78dBm

+ Received OK: 100 (Transmitted packet number: 100)

(Question 1)

- At 710m Distance between transmitter and reciver, a lot of CRC errors occurred.

- status on SmartRF studio :

+ Average RSSI: -80.78dBm

+ Received OK: 4 ~ 10 (Transmitted packet number: 100)

Q1)

Even if average RSSI is good, a lot of CRC errors occurred and Received OK numbers is low.

In Korea, LTE frequency band is near 869MHz ~ 894MHz. So, i think that LTE frequency may be interference with our testing frequency band.

As you know, ZigBee chip has the energy detection function which can measure RF level around nearby nodes. 

Does CC1200 has the similar function? If available, plze let me guide.

Q2)

On "Packet RX tab" of smartRF studio, PER and BER value is displayed when TX, RX test is finished.

SmartRF studio measure the PER and then this value is converted to BER value. right?

Q3)

On "Packet RX tab" of smartRF studio, received OK and PER value is overlap "Received OK and Packet Error Rate" setence.

Do you have solution to see the exact Received OK value and PER value?

 

Thank you.

Best and Regards,

Kwangbog HAM.

  • 0
    TI__Guru**** 317180 points
    Q1: You can get a fairly good indication if you at the Rx side use cont. Rx and look at the RSSI (without turning on the Tx side).

    Are you able to do a range test on a frequency further away from the LTE frequencies?

    Q2: Yes

    Q3: Could you post a screenshot? If you expand the window to full screen I don't see this.
  • 0 in reply to TER
    Intellectual 390 points

    Dear TER,

    Thank you for your advice.

    Q1:

    We used the CC1200K on TX and RX side and result is checked on smartRF studio.

    What we want to get is not the only RSSI value. Other factor is important values.

    We suggest that if we can know the energy detection value just like ZigBee chip:

    First, we will check the value in shield room. (For example, energy detection value is 0 because there is no interference from other frequency band)

    Second, we will go to site and check. how does this value be changed.

    Please, let me know method and procedure which i suggest.

    If it's impossible, we need other advices.

    Q2: That's OK.

    Q3: Below pictures.

    The resolution of testing PC has 1920 x 1080.

    But, 1024 x 768 resolution has the same problem.

  • 0 in reply to Kwangbog Ham
    TI__Guru**** 317180 points
    I'm not familiar with how the 'energy detection value' in Zigbee works but from a short google stunt it looks like it uses RSSI.

    CC1200 has nothing called 'energy detection value' but RSSI tells you the energy you have in the channel you have selected. If you stand in a shielded room you should read a RSSI in cont Rx around -120 dBm. If you do the same at the test site you will probably see a higher value. Since you start getting a lot of CRC errors around - 80 dBm I would assume you will see a noise floor around -90 dBm at the test location.

    Q3: I don't see this when I test.